Ridley,
A video card change is not that hard. It is handy to have another PC to access the internet for help.
First, before breaking the seal and opening the case, see if you have a manual that will tell how many expansion slots you have, and the type of slot (PCI, AGP, PCI-E). Most PCs with on-board video will only have PCI expansion slots. You can get a video card for PCI, but they are a little harder to find. PCI and PCI-E are different.
If your interested in learning to build PCs, the best way to start is to upgrade an existing sysem. Good luck.
Gunner