What wire do I need to connect a new radio to the speakers?

What is your question?

I recently took out the stock radio out of my car. I bought a bluetooth double din radio. I have the wires connected and fused to the radio and car,but I don't have any wires to connect the new radio to my speakers, so sound won't come out. The radio itself turns on because it's connected to my car, but no noise will come out because it's not conncted to my speakers. Can someone please tell me where/what wire I need to buy to connect it to the speakers?

How long has your 2002 Mercedes-Benz ML320 had this problem?

A few weeks