RightToClick installs two icons on your browser - once up in the navigation bar, and another in the status bar. Clicking once on either will enable RightToClick. Once it's enabled, you should be able to right-click, get rid of popup alerts and overcome annoying features that make certain websites a pain in the neck.
RightToClick also has some pretty complicated configuration options. These aren't well explained, but will be surplus to most users' needs anyway. Even so, if you want to get at really deeply restricted website elements, these options are definitely worth a look.