bleeping sound when I turned on after ram upgrade

what model iMac do you have?

assuming your iMac was working before you upgraded the RAM, the beep(s) after power up probably means the RAM is not installed correctly (maybe just not seated correctly in the socket), or perhaps the wrong type or a dead RAM module. basically the power-on self test does a memory test before booting into Mac OS, and beeps if the test fails for whatever reason.

but take a look at this and see if this helps:

http://support.apple.com/kb/HT1547

follow the additional link at the bottom if yours is an Intel iMac.

try taking the RAM out and re-seating it firmly in the socket(s) before powering up again