If you are wanting to go to an extension's options page by using a bookmark you can go to Tools -> Extensions and Themes or about:addons in the address bar. In the list of extensions, there should be a button to go to its options page. You can then copy what it shows in the address bar and then add that as the URL for a bookmark. You might also be able to click the Star symbol in the address bar to add it as a bookmark. If you mean something else, might explain.