Instructions
+ Download them here: Download Windlights+ Extract it.
+ copy the windlights within the folder to:
Windows XP: C:\Documents and Settings\USERNAME\Application Data\SecondLife\user_settings\windlight\skies
Windows Vista, Windows 7: C:\Users\USERNAME\AppData\Roaming\SecondLife\user_settings\windlight\skies
Mac: Go menu > Go to Folder and paste in: ~/Library/Application Support/SecondLife/user_settings/windlight/skies
+ Done! :)
Start your viewer and enjoy.