You need to decide whether you're up to the challenge. If the FAQ for hooking a working computer up to an amp is over your head, you will have difficulty succeeding at this project. Since every install is custom, there is no manual to follow and you will have to improvise constantly. While you can ask questions on this forum, people are hesitant to "spoon-feed" someone through a car PC install.
Also, while it is possible to put a car PC in your car and be able to return it to stock, it requires careful planning. I suggest checking out some of the projects in the "Show off your project" forum. If the projects seem to be over your head, I wouldn't do it. You could easily damage your car and cost yourself major repair bills.