You automatically receive your Levitation Learners permit which will allow you to levitate only inside her mind. Pull out your levitation ball and run and jump over the first gap. When you go to jump over the second one pull the 'Left Trigger' to use it to float a bit. Now you've gotta go find Milla on the other side of the party.
Immediately to your right is the Dufflebag tag. Before we head into the real party, jump down and on the right side in the back corner is a Cobweb, then jump back up with your new levitation ball or use the netting on the wall to climb back up. Now cross the bridge into the real party.
In this next room you'll need to get out your levitation ball and roll around the bowl and jump through all 3 hoops, after doing so some flower type platforms will come down that you can use to move up. After you reach the top Milla is kind enough to put a "ball return" at the bottom so that you can get back up here real easy if you fall. She also tells you your next objective which is to float through the rings and get them spinning again.
You'll see some people partying next to you here, you'll also find good old Dufflebag here. Jump up to the platform in front of the rings and then jump over to the rings and hover through them. Milla will bring out another ball return and move the platform your on up a bit higher.
There's two platforms near by higher than you, jump up on the closest one and Milla will tell you about the fan blowing air, if you jump into the airstream and float you'll get pushed by it to make it to the other side of the area. You'll more than likely get blown into the ladder so make sure you climb down it to grab the Steamer Trunk tag. Then climb up the ladder.
Up here you'll see a big pinball type launcher, but before jumping in there straight across in front of you is the Hatbox tag. It'll take some rolling, but up to the left of where you came in is the Steamer Trunk. Now over to the ramp area leading to the plunger, get up on the high end of it and roll down into the plunger with as much speed as possible, as a result it will launch you back real good and when you're in the air you can float down onto the blue platform. This platform will then bounce you across a series of other ones landing you on a nice flower one that floats up.
Another ball return will appear now. When this platform is at the height of its ascent jump off it onto the railing, there will be a cobweb right in front of you. Walk around this area up here and you'll come across the Hatbox. You may have noticed by now all the circles along the railing that aren't spinning, jump up on the railing to grind through them all and get them turning.
There is now a moving platform that you can jump up on. Jump on to the party platform and head back and to the left where you can jump off and float over to the ledge with some doors on it, punch the doors to open them.
When you get in here some Censors and Bomb dudes will pop out right next to the Purse tag. Punch the door on the other end of this hallway to get to another bowl with some more Censors and a Vault containing the "Milla's Adventure" memory. Get out your ball and roll around a bit then jump up out of the bowl to grab on to the fencing around it.
Climb up the fence as high as you can and jump towards the platform in the middle with all kinds of hazards on it. Lucky for you when you're levitating you're protected from all these things! Except the spikes, you can't ever get away from something like that sadly. Levitate over the mess and jump to the pole in the middle, climb up it and jump to the flower platform near by. A ball return now appears at the bottom.
Keep your eyes up a bit and you'll see a moving platform coming around, use your levitation to jump up on to here. Watch out for the big green thing stretching across the room because it's a wall and you can't go through it, you'll need to jump over top of it and land back on the platform. As you go around you'll now notice another platform towards the middle and a door along the right side.
First go for the platform in the middle and then jump to the blue bouncer platform and you'll get shot over to where the Purse is located. From here you can jump and float all the way over to the doors and then punch them to open them. Some Censors will immediately appear. Walk through the opening in front of you.
Whip out your ball and roll through this crazy checkered tube to get to the racecourse part of the party. You'll need to do the whole race while on your levitation ball. Throughout the course there will be several obstacles. The things that look like lowercase n's you can go in the middle of and they will give you speed boosts. You'll have to use these to win. Most everything else will just stop you and that will significantly decrease your chance of winning the race. You do need to get in first place to continue on in the level.
There's not really any big strategy to this race, just avoid things that will slow you down, get all the boosters you can, and stay on your ball! After you win the race you'll be taken to a new area, you're almost at the real party!
Right smack in the middle of this area is the Suitcase Tag so don't forget to grab it. Also, directly underneath where you came in is a Cobweb. If you haven't figured it out yet, these platforms are spitting up an airstream that will allow you to float up higher when you float overtop of them.
First, from where you came in, there are a few of these platforms directly to the side, jump on the first then float to the second then the third which will float you up real high. From here up against the wall you'll find a small ledge with an item that increases the amount of Psi-Blast shots you can hold. Now go back again to where you came in the room.
Straight out in front of you is a regular platform with an airstream platform in front of it, work your way up these airstreams here. The last one will take you up by a ledge with a button on it you need to punch to activate. After punching the button the middle fan will start to move, it's time to get some more rings spinning!
I'd recommend floating up until you see a platform then fall through it, then float up again to the next one, fall and repeat. When you're done the shocks will go away from the door and you can float up there where you'll find the Purse, then punch through the door to move on.
In this room there's a bunch of crazy blue tube type things leading down to the middle, there's one right underneath you when you walk in, so if you go into the middle then head to the next one to the right, on the far side of it is a Cobweb. Jump on the blue bouncer in the middle of the floor to get back up and then jump over to the party platform to find Milla.
You've now gained your Levitation merit badge! This gives you the freedom to levitate anywhere you want!