Need some Mac Guru help - I haven't a clue

Hi guys, I know PC's but am working on a mac that is a desktop, but has the hard drive and motherboard in a half circle casing and the monitor has a neck and is a flat display. I've never seen anything like it but it's a Mac. It's hanging up before the OS loads, being it's getting a continuous "processing" circle that keeps refreshing but the desktop never loads. No POST test, just straight to loading this hanging desktop (I don't know if Macs show POST tests). I want to reformat with the OS disks but cannot get the cd rom drive open being there is no button on it to make the cd rom drive open to put the cd in and the OS hangs before I can do it through software. Is there some kind of hotkey that makes the cd rom drive open to I can put the cd in it?

Thanks guys, sorry for the lame description but I'm totally out of my element here.

The computer you're describing is an iMac G4. For specs and manuals, check
http://www.apple.com/support/imac/g4/

And seriously, read the manual.

To open the optical drive, you push the eject key on the original keyboard, which should be labelled with the ⏏ symbol, like the CD drive in your car or home stereo.

If it's missing the original keyboard, you can fake it using the F12 key

The G4 iMac. Heres a link to manually eject the disk

http://docs.info.apple.com/article.html?artnum=58465

There is no visible POST test on the screen but there is a POST. Do you have speakers plugged in? If so do you hear a startup sound? Kind of musical. If so it's passing it's POST. That computer is an iMac G4.

What keyboard do you have plugged in? Is it an Apple keyboard? most have an Eject key. What does the keyboard look like?

I have never really gotten to mess with the CDROM door on a iMac G4 but I know booting with the mouse button held down ejects a CD in the drive. See if that will open it if there is no Eject button on the keyboard. You hold down the Mouse button right after the startup sound and keep it down.

Maybe someone else with an iMac G4 will chime in.

Your awesome guys, thanks. p.s. There is no sound on bootup but there was before it went DOA