brake warning light is on I need new front brakes

Here are guides that will help with this however, you said in the subject that you wanted rear brakes but in the post you asked for the front. I suspect you need the front so here is a guide that will help with this:

https://www.2carpros.com/articles/how-to-replace-front-brake-pads-and-rotors-fwd

Below is the process from the manual on this. Please run through this material and let us know what other info you need. Thanks