How to hook up metra 70-2003 wire harness to aftermarket stereo?

i ordered a metra 70-2003 wire harness and an aftermarket stereo off ebay. now i know the harness fits in my car because i just checked it to make sure. im a big DIY-er so i really want to learn how to do this. the stereo's harness has these metal tips with a plastic cover around it but it doesnt close or anything please help me install this. i can give pictures to what the wire harness and the stereo's harness look like but i guess i will have to pm them since there isnt a way to add them to this. any help will be greatly appreciated