This is a very time-consuming event. I would suggest you do a Google search for how to's, along with you tube videos. There are some excellent videos that will get you started. It's going to be a long road. So grab that cup of Joe, sit back and start reading. It's not something that you can read for a few minutes, like how do you install a new skin for your car/truck. into the game. This is something that you will always be learning about.
You also say you need help installing. Is this a bootleg copy, as instructions should have come with it. Also, what version is it?