The Wave Climber by Little Tikes is a great toy. Ours arrived when our twins were less than two years old, and they took to it immediately. 8½ years later it still looks new.
1. Start by assembling the green and yellow walls. Some force (or a big mallet) is required to push the locking tabs through the holes.
2. Add the orange wall. Attach it to the green wall but leave it separate for now from the yellow wall.
3. Insert the floor. The far corner, at the intersection of the green and yellow walls, needs to go in first.
4. Leave the walls spread to make room for the slide
5. Insert the slide. Make sure it slips beneath the floor so that it will be locked in.
6. Lock together the orange and yellow walls, add the stabilizing feet, and you're done.