Looking at this picture you can see the terminals at the top.
This installation has one speaker hooked up on the right, and the power inputs hooked up on the left.
The inputs will be power on the left, 12 volts positive (V+); a signal wire for to power on the amp that's 12 volts positive too, (V+, It's usually a yellow wire that comes out of the car stereo called To Antenna, or To Amp. and the third connector on the left is a Ground, or 12 volts Negative (12-). Look for the labels V+ and V- to get the power connectors in the right places. (I can't tell from the picture which is which)
On the left side is the Speakers, Each speaker has a positive and negative lead, and the terminals on the amp are labeled Left + and Left - and Right + and Right - .
Align the speaker leads to the terminals (in cars a negative lead usually has a stripe running along the length of it, and a positive has no stripe).
On the other side of the amp are RCA sockets, one red one white. Any low signal can plug into these, from an Ipod to a turntable. Your car stereo, or EQ, will have RCA outputs that can connect to these with an RCA Patch cord, which has plugs on both ends that will fit into the RCA sockets. Whatever signal goes into the RCA inputs is amplified out of the speakers when it works.