If you have the ability to install a hard drive, you must have physical access to the machine itself, and if you have physical access to the machine, you can access BIOS simply by pressing a certain key during boot-up (typically it's something like F8 or Del or F12 but it can vary) During boot-up, you should see something like "Press [key] to enter Setup". Press whatever key it says.
Overall, it would be helpful to include more detailed info about your machine (make, model, etc). If things were working fine prior to the RAM upgrade, then my first guess is that the new RAM is incompatible with your mobo (eg, the RAM is faster than the mobo can handle) Have you tried putting the old RAM back in, to see if the problem goes away? If it does, then the new RAM is the issue - either it's defective, or it's incompatible with your mobo.
Also, be sure that you don't have a floppy in the floppy drive, and that your hard drives are jumpered correctly and installed correctly (meaning check both ends of the ribbon cable to make sure they are seated securely) Good luck with it