Just get a wiring harness from any car audio store for your specific vehicle. All Toyotas from '87 up use the same connector for the radio. What you'll be buying (about 10-15 bucks) is a harness that plugs into the Toyota connector, and has wires coming out that you connect to the aftermarket stereo. The wires should be color coded to match the stereo wires.
http://www.crutchfield.com/cgi-bin/S...=0&cc=01&avf=N
Good Luck.