itunes wouldnt open

Ok i reformated my mac because itunes wouldnt open. i had 10.5.8 and restored it to 10.5.3 thinking i could update all the software when done. NOPE finder wouldnt open and everything wouldnt open. the only thing i could do is enter my network password. I now have snow leopard and the cd icon wont show up and cant install 10.6. any help?

Thanks

Insert your SL CD, restart your mac holding down the C key which will boot from the disc.
Then based on your problem, if you have backed up onto an external drive, I'd recommend doing a clean install.
To do this, once you choose your language, in the menu bar go to disk utilities, and choose erase your Macintosh HD, and then quit utilities, and continue with installation.
At the end you will be given options to restore your system from your back up!