Building own lot in Sims 2- Terrain not flat Options?

I am trying to build my own house in Sims 2 and I'm maybe being a little dense if I put a foundation on at ground level, you need a small flight of stairs to access the house and I can't find such a thing in the build menu, or if you build straight on to the ground you can't put walls, doors etc where you want them cos there are slopes in the way, help please I just wanna make a nice home for my sims LOL!!