Finding new fonts to use isn't hard, as there are many sites such as 1001 Free Fonts and DaFont that offer free fonts for download. Some sites, like Font Squirrel, even offer fonts that are completely free for commercial use.
Installing new fonts is also easy, as modern operating systems allow you to simply right-click the font file (double-click in Mac) and click "Install." In older operating systems that don't offer this option, just move the font file to the system's font folder - C:\Windows\Fonts or C:\WINNT\Fonts in Windows and /Library/Fonts in Mac.