- Open the Themes Manager (in Firefox 2+ it's Tools - Add-ons - Themes, in Firefox 1.x it's Tools - Themes)
- select the installed theme
- click the Use Theme button
To install a Firefox theme offline, drag the downloaded JAR file on the Add-ons Manager window. Note: do NOT double-click the file! You will end up either getting error message or opening the archive.



| Yahoo ID: redfatlazycat