How do you enter BIOS mode?
Bios is also called setup, you enter it by tapping a key repeatedly at startup, this key could be listed during post, the initial startup screen, sometimes delete, F1, F2, F12, depends on the computer.
What brand computer is it?
By "install the video card" do you mean slot & screw it in?
And finally, even if i mess this up, even though i have removed the drivers for the onboard, will i always be able to return the whole computer to it's last working settings by removing the battery? (I ask this because although I am willing to attempt to install the card myself, I have decided that if there is any chance I can accidentaly damage my computer permenantely, I will not do it myself, but ask my friend to do it for me (who is perfectely competent with computers.)
Its fairly simple as long as you take precautions, like esd(electro static discharge) To remove static from your body simply touch the case before touching anything inside the computer or the video card. Work on a tile or wood floor not carpet
Also important is to make sure the card is inserted completely in the slot.
I assume you read the manual for the card, if it requires a additional power connector make sure its pluged in.
Correct me if I'm wrong, but if I remove the drivers for the onboard how will I be able to get a picture on my monitor? (which i will need, in order to install the new driver)
After driver removal you will still be able to see, its just that you will then be usig a standard vga windows driver, it won't be pretty but trust me you will be able to see, it will be the same when you boot to vga mode with the new card, till you get the new driver installed.
Really appreciate your help Dobby btw, im just terrified I'll mess up my computer somehow.
I completely understand, you will be ok as long as you are good with the mechanics, take your time and double check things and of coarse follow instructions