Not really a new pc, but...

It's not a new PC. I just used a couple comps that were laying around the house. This is my first time doing this, and so far I have gotten everything together. I push the power button and I see the lights on my disc drives light up, and I hear and feel the HDD spinning, yet there is no video on my monitor. When the monitor is unplugged from the comp, there is a repeating message saying no signal. I plug it in and the message goes away. So, I assume that means that it has made a connection with the MB, but maybe I didn't connect a wire somewhere or something. Need help with this.

This is what I have:

Motherboard: Not sure, AMD build, 2 memory slots, 2 IDE slots, 1 Floppy slot, built in sound and video

Hard Drive: Seagate Barracuda ATA IV, 40 Gbytes, Model ST340016A

DVD-ROM: Delta, OIP-DV1200A, Manufactured February 2001

CD-ROM: Mitsumi, Model CR-4809TE, Manufactured December 2001

Power Unit: EZ Media, QC Pass 2003, Pentium 4 sticker (dunno if that means much).

Processor: AMD Athlon 64, Approx. 2001

NOTE: Power Unit is '03 because it had to be replaced. Comp was originally built in about 2001.

If you could use pictures to help explain what to do, that would be quite helpful. Thanks.