Where can I get option for Add-Ons in Safari?

Can anybody help me with the Add-ons in Safari for Windows XP? I am not getting interactive menus for installing new add-ons and themes for my Safari. When I click on the Window add-on option in Safari, it shows me the complete list of installed add-ons as a web page. But I was expecting the list of Add-ons in a separate window from where I can install new Add-ons and themes to customize my Safari according to my taste.

This kind of facility is available in Mozilla’s Firefox. Its add-on option shows up the current installed add-ons and themes. It also has options which directly take the user to Mozilla’s webpage. From there you can select different extensions and themes to be installed on for your Firefox. Apple should also offer a similar kind of facility for its customers. Of course Safari’s method is still more simple than with Microsoft’s Internet Explorer. I have tried a lot to find a simple way to install new themes and add-ons but didn’t get any such option. May be its there as sub-option under some tab (which I am guessing only), but still there should be an easy way to get it because everyone uses these kind of options to dress up his browser according to his preferences and should be accessible easily.

Safari’s way to show add-ons:

Mozilla’s way: