<a href="https://chrome.google.com/webstore/detail/tab-colorizer-customize-y/nkdjooaecafkkldnkaokhpaindamlngj" rel="nofollow">https://chrome.google.com/webstore/detail/tab-colorizer-customize-y/nkdjooaecafkkldnkaokhpaindamlngj</a> is the chrome extension list. There is instructions there. As Keithcurtis said, it is not Roll20 and is offtopic for the site. For more help, you will need to contact the creator of that extension.