Spring RTS Engine

ok, first off i know pretty much nothing about making mods or even what programs u use to make 3D things (never paid attention in my CAD class ) and i know that starting from nothing will take awhile but i was wondering, if someone wanted to start learning how to make mods for this and siggys and stuff like that, is there books or sumtin or a website that could teach you? just wondering cuz i wanted to start moding games and making my own siggys =/

I think that modding is very diferent for each game, since (I believe) most games havent been made looking forward for persons who might want to mod then, but if you know how to program then it shouldnt be that hard :)