Difficulty upgrading from OSX 10.5.8 to 10.6.3

So I have been having difficulties upgrading my 2008 24 inch intel iMac with 10.5.8 to 10.6.3. I bought the retail version of snow leopard and recieved the disc yesterday. So after opening the package I inserted the disc into the drive. And theeennn.... Nothing. No icon showed up, no disc spinning. Just nothing. I tried multiple eject disc methods, but the mac doesn't even recognize that there is a disc inserted? Ok, so i'll just try to reboot the computer and see if it shows up? After turning it off, i press the power button and let it boot up. But it doesn't. It just sits there at the first white screen. Now i'm really confused.. I try one more time and manage to get it to get to the apple logo. After sitting at that for way longer than I should have, it finally boots. After a few seconds the icon for the disc shows up on the screen. So far so good.... But once I attempt to open the icon, the screen just flickers for a second then goes back to normal. Nothing opens, nothing changes. Very odd. So I attempt to just eject the disc. After going and clicking on the eject icon on the toolbar, the disc refuses to eject. But the system believes that it successfully ejected, so the icon dissapears and the system stops recognizing the disc. So i attempt a couple of eject techniques, but nothing seems to work. I try rebooting multiple times, (many of which leave me sitting at a blank white screen) and a few attempts at booting from the disc,but nothing seems to give off any kind of result.

I'm honestly out of ideas as to what to do. At first I thought maybe just a dirty drive, but the fact that not even the force eject techniques work changed my mind. Does anyone have any idea what possibly could be going on? Perhaps it's something very simple that i'm just missing, but I really don't know. Just a reminder, the iMac I am using is a late 2008 24inch Intel, on OSX 10.5.8, and am attempting to upgrade to Snow Leopard 10.6.3.

Any and all help is appreciated! Thanks!