[Plugin: AddThis WordPress Plugin (drop-down version)] Customize it?

Hi! I’m using the AddThis plugin for WordPress, it’s actually my first time testing the Addthis service. I know it can be customized, because I’ve seen it in many many sites, but that’s my question: How can I customize the plugin?… I want to be able to select the web2.0 sites of my choice… I’ve tried to edit the plugin in the plugin editor but it has nothing I can work with…

Any ideas? Any recomendation? Thanks in advance…

Link to Plugin: https://blog.addthis.com/?p=32