How do I replace a starter and where is it located on the car

you sound like a rookie- the starter motor is alongside, under the engine- if you are just now contemplating doing your own work, I suggest reading up on the basic mechanical workings of automobiles- try the library- I admire the idea, doing your own work, but you will need a lot of tools and a lot of band-aids- working on cars was so much easier 40 years ago-

A 1994 Oldsmobile Cutlass where do the starter stat set at on the car