Most programs in Windows use the fonts that are installed with the operating system. Some programs such as Adobe Photoshop have their own fonts folder but that is more the exception than the rule. You can easily install more fonts into Windows by going to fonts in the control panel and then clicking file>install new font. You can go to this webpage for more detailed instructions on how to install fonts in windows.
NOTE: before you go crazy installing hundreds of new fonts on your computer you should know that having too many fonts installed can slow down your system and the programs that use these fonts. See this webpage for more information on that subject.One more precaution is that if you intend to use unusual fonts for writing documents, instant messaging, or emails keep in mind that other computers that don't have these fonts installed will not be able to see them properly.If you want to view and manage fonts without installing ALL of them, you can use a font manager. This helps if you download several fonts and want to preview how they look before you install them to your Windows font folder. Additionally there are programs that will help you to create your own fonts. Some of these programs are free and some are not. You can find them complete with user reviews at typical download sites such as www.download.com or www.tucows.com
Note: that sometimes these new fonts will show up at the bottom of the drop down fonts list in the program rather than in alphabetical order. Learn more about computer fonts. If you are wondering where to get fonts there are thousands of free fonts available on the internet so we'd recommend doing an Internet search on fonts or going to a site like this to find what you are interested in experimenting with. http://www.1001freefonts.com/