|"I can't increase my RAM using bios"|
Of course not. RAM is increased by physically installing more. If you mean graphics memory, you'll still need to install more system RAM for the graphics memory to increase. That doesn't necessarily mean graphics performance will increase because the graphics processor unit (GPU) is the limiting factor. Most likely the GPU is integrated into the motherboard & cannot be upgraded.
"My HP brand is HP G62 Notebook PC"
G62 is the series. The characters that come after that will nail down your specs. For example, here's the specs for a G62-340US:
That laptop can handle up to 8GB RAM (2 x 4GB). I'm guessing yours can handle the same amount but you'd need a 64-bit version of Windows to take advantage of it.
EDIT: I just found this:
message edited by riider