To start, use the sample objects that come with AC3D.
Cushion tutorial:
http://leezu-tutorials.blogspot.com/...beginners.html
Modeling a Pear with AC3D YouTube video
http://www.youtube.com/watch?v=Y8RC5aJuWks
For more advanced shapes, you'll need to use the TCE (Texture Coordinate Editor - Tools menu).
Advance - Sculpted Prims from Existing 3D Models
http://www.independentdeveloper.com/...rom_existing_3
For more detailed info on sculpties - see:
http://www.ccccybernetics.com/