I think they either jump onto the second level, or theres some access to it from the purple thing on the left, donno about that though.
Anyway theres fiddle sticks on the second level that the pig hops up on, and theres a hole in the floor of the top level to climb through (look next to the pig on the top level)
yup yup, onto the pigloo on the left through a hole in the side of the bin, onto the fiddlesticks, and up through the hole too the top... Gee i dont think my girl would be brave enough to go all the way up htat thing, she gets scared just sitting on her grid futon sometimes lol.