It has been a while, but as far as I can remember I just went to the TB main web page, downloaded the program (click on "home" tab on this page). Then I went to YT and TB said I needed to login. Next thing I knew there was an icon up on top of the browser. Same way for both Firefox and Chrome. Not sure if the login was necessary for it to show up on the bar, but it is just the way I happened to do it.