Web cams. I am thinking of buying a webcam so that I can keep in touch visually with a friend

Question

I am thinking of buying a webcam so that I can keep in touch visually with a friend through our computers. Neither of us has used a webcam before and we are both non-technical. Can you please advise us what we need to check out on our PCs to find out if we can use a webcam with them and what else do we need to know, such as the most suitable webcam?