In most browswer the shortcut key combination to add a bookmark or favorite is Ctrl-D. Surf to http://www.teens-online.com and hit Ctrl-D to create a bookmark.
Netscape
If you're using Netscape go to http://www.teens-online.com. Once there, click on the menu bar "Bookmarks" then click "Add Bookmark"
Internet Explorer
If you're using Internet Explorer go to http://www.teens-online.com. Once there, pull down the "Favorites" menu then click "Add To Favorites".