How can i hook up my subwoofer in my truck? ?

I have a little 8" sub that bangs. Its the kind that has the amp already installed in the sub. I had it in my old car, had my buddy hook it up for me. When i sold the car i had the guy buying it, take it out for me. I want to hook it up in my truck now. Now, i will tell you im not very electronically intelligent at all. Hence the reason why i had my buddy hook it up for me. But sadly he's not around anymore. I was wondering if someone could help me out or tell me how to hook it up. Any help would be greatly appreciated. Thanks.