hey, congrats on your runner purchase. i bought a black 02 sport edition this summer and i love it!
as for your stereo question, let me tell you and everybody else here about a GREAT resource for these questions.
www.the12volt.com
they have archives of wiring diagrams for pretty much every vehicle and i know they have one for the runner. it will tell you what the wire colors are, and where to find them. also, if you have any other tech questions there are professional installers on the forum everyday that answer your questions on anything electrical for vehicles...
good luck!