Getting started using the Selenium build system can be tough. Here are a few pointers to the Rake tasks that you can use.
There are quite a lot more tasks in there than rake --tasks shows you. This walkthrough introduces some of the tasks.
Prepare your development environment for the Selenium IDE Firefox plugin:
rake se_ide:setup_proxy
This sets up symlinks between folders, and makes it possible to start developing in "proxy mode" as Mozilla's docs calls running a plugin from a text file with the path to the extension's files.
You can drop these symlinks by calling:
rake se_ide:remove_proxy
Call
rake xpi
Run rake without any parameters to invoke rake test, the default task. This runs a bunch of tests against the WebDriver code.