Help! I'm Electrically Challenged.

Recently I bought an aftermarket stereo but can't for the life of me figure out which wires are supposed to be connected to each other. Can someone please help me? The stereo I have is a Pioneer model number DEH-2000MP. I would stick with the factory stereo but it just doesn't cut it anymore. It doesn't even have a place to play a cassette.

The radio came with a wiring diagram or labled wires. An installation harness can be prchased that has the same plug as your factory harness. This installation harness will have a diagram of what wire will need to be attatched the the radio. This will be the easiest way for you to install.

It will look something like this
http://www.myinstallkit.com/pics/3139_lg.jpg

I already tried using the harness that is supposed to click into the existing radio harness and it didn't work. So now I want to know how to connect each wire to its counterpart seperately.

All you need is a wiring diagram for the radio. If somebody has one I'm sure they will get it to you otherwise your local library will typically have repair manuals and sometimes access to alldata which will have factory wiring diagrams for you metro.

What year is your metro?

There are 8 wires for the speakers (two wires for each speaker) ground wire, battery 12v, ignition 12v. The new radio might have a wire for a power antenna (not used) The hardest part is to identify what colour wires are which speaker. There may be a diagram for the wiring on the new stereo. You can use a 9v battery to identify the car's speaker wiring. The speaker will make a crackling sound when you connect the battery to the speaker wires. Don't hold it on very long. You can damage the speaker.

Try going here and downloading the owners manual. It probably has a wiring diagram.
http://www.pioneerelectronics.com/PUSA/Products/CarAudioVideo/Source/CD-Players/DEH-2000MP?tab=D
I believe the information you are after is here on page 5
http://www.google.com/search?hl=en&q=pioneer+deh-2000mp+wiring+diagram&start=10&sa=N

Thanks for everyone's help I got this installed on Saturday. Actually had the wrong wiring harness the first time I tried to install everything.