well as you seem a bit of a noob to gta modding ill tell you straight - modding is EXTREMELY hard work. a car mod can take months to make. well, search google for zmodeler, its the software i use for car modding. youll need IMG tool and txd workshop 3.5+. youll need photoshop or paint shop pro. if you want to buy photoshop its gonna cost £300+. i wouldnt bother, you just seem an ambitious noob.