DrThraX in Shp builder you make the graphics and animation for shp based units/buildings/infantry, to actualy change/create the building you have to start messing up with the .ini files rules.ini ar.ini , sound.ini you can figure out what it does, ai.ini controls the Artificial Inteligence (yeah right) also known as the AI.
Since you say you're noob i recomend for al noobs Tibed. You can get it from
http://www.tibed.net if you wan'a get into the graphics/animation of the game i recomed you to get a voxel editor and a Hva editor olso. And remember the Xcc utilities are a Ra2/Yr 's modder best friend so....