Ok, there are two ways.
First way:
this is the easiest way, but you will need a big dragon.
1. Wear your dragon, then fly where you will want to stand (e.g. the big scoop roof)
2. buy a bunny potion, then drink it.
3. take your dragon off
4. cancel the potion
5. DONE!
Second way
1. buy a bubble potion
2. if you want to, jump onto a door (click the top of the door, jump just before it)
3. buy a dragon tears potion
4. go into your backpack
5. move your mouse out of the backpack, jump, and quickly drink the dragon tears potion
6. if you did it right, you should be standing on a wall/roof
Hope this helps!
From Misty :-)