Man, I'll have to take my computer in to a comp shop, sounds a bit out of my depth
To be perfectly honest, it's nowhere near as hard as it sounds. Almost all computer parts are semi-idiotproof, since they 'key' to the correct slot, and won't fit in the wrong place. Try cracking your case open and looking carefully at the stuff inside.
Here's the major parts to any PC:
CPU (You don't screw with this usually. It's the chip that has a fan bolted and glued to it with thermal gel. Leave it alone till you are SURE of what you are doing).
Motherboard (The giant board everything is attached to)
Power supply (The box that you hook the power cable into. It runs about 15 billion various sized wires to all the parts of the PC)
RAM (These are thin chips that snap into slots on the motherboard. You can safely remove them while the PC is off and look at them, then snap them back in place)
GPU (Video Card. This can vary WIDELY on pc's, from something about 2x the size of a ram board to something that looks like you could club an elk to death with it. It snaps into the motherboard via a slot, and may or may not have it's own fan and power plugin.)
Hard Drive (This is usually bolted into a rack inside the case. It holds all your data).
CD/DVD ROM/Burner (The device that reads your CD's. It is bolted into the case like the hard drive, but it has an external slot it faces.)
Running between these are cables and ribbons that can be easily disconnected and reconnected. Honestly, so long as you don't go spiking parts around or dumping peanut butter in there, you can fiddle with parts inside a PC all you want and not break anything, as chip boards are surprisingly durable. Just be sure to turn it off and unplug it first and always touch something metal and grounded before you jam your hand in there, as a single carpet spark can fry whatever it hits, even if it's so small you don't see it.
I'd encourage you to fiddle with your PC and figure out how to disassemble and reassemble it yourself. I guarantee you, you will save at LEAST 25% by ordering your own parts and snapping them into place vs going to a computer chopshop. Those places charge ruinous markups plus hourly fees.