There are a lot of places on the web where you can find free fonts. Here are three places that I have used. They each have a wide variety of types.
Almost all the fonts are screen fonts. That means that they will be perfectly usable for making images for web sites, but they may not be good enough for using for printin. If you are designing art books then you need to include commercial fonts in your budget.
If you are unsure how to install new fonts on your computer, there is a step-by-step guide available from MyFonts.com