What do I have to do?

Hi, I have no idea what so ever of modelling, but I made wall models out of Oinker primatives and once I finished, I imported it to my map and made it as a destructible and set the pathing to walkable, but they don't seem to go on top of it. Now the question is, how do you make things go on top with out putting height raisers? you know like xxMorpheusxx's walls, were they automatically appear on top

Find the "Invisible Platform" (Otip) in Object editor. Now change the model file to your wall.

Thats should work!