To add or install fonts on Windows, follow these simple steps:

1. Download the fonts. There is a good collection of free truetype fonts at WebToolHub Fonts Collection.
   
2. Unzip the font files (for .zip files) and put the extracted .ttf files on your hard disk
3. Click Start and then click on "Run"
4. In the next pop up window that appears, type %windir%\fonts
5. Click OK
6. Another pop up will appear with the list of available fonts.
   
7. Click on the "File" menu, then click Install New Font.
8. A pop up window will appear with a few boxes. There will be titles like "List of fonts", "Folders:" and "Drives"
   
9. In the Drives box, click the drive that contains the font that you want to add.
10. In the Folders box, click the folder that contains the font that you want to add, and then click OK.
11. In the List of fonts box, select the font that you want to add. You can also select more than one font at a time by pressing and holding the CTRL key.
12. Click to select the Copy Fonts To Fonts Folder check box. The new font is saved in the Windows\Fonts folder.
13. Click OK.

If you want to remove fonts, steps are available at How to Remove a Font.