Two Plus Two Older Archives - Multiple Monitors

I want to start out by mentioning that I no very little about computers. However, I would like to get another monitor which would allow me to multi-table. The only problem is that I have no clue how to hook up a second monitor. Can anyone give me some advice or a website to check out which would allow me to hook up a second monitor to my computer. Also, when people have multiple monitors do they need another mouse, or can you hook it up so that you can just use one mouse?

P.S. Feel free to offer any other information on this topic.