I am an installer at Best Buy and am MECP Certified......if you have a 2 channel amp and u wanna bridge it to 1 sub....first you have to know the impedence (ohm rating) of the sub..and what ohm rating the amp is most efficient at...if you dont, you can toast ur amp pretty quickly. To be honest, if your sub can handle 1500w..it's probably a dual voice coil sub..which, in that case you'd probably run a separate channel to each coil...it all depends on the specs of the amp and the sub. You can run it parallel or series it. For a good reference.. go to
http://rockfordfosgate.com/rftech/ for some more help. Or, if you get your specs of everything, I can help you. To answer your first, basic, question: on the amp there should be the words "bridged" above the speaker channel outputs where the (+ and -) are. If not, you simply take the positive of the left channel and the negative of the right channel...boom, you're bridged.