First up, you will connect to the WebIDE (running on the Pi) using a different computer (not the Pi). The client computer must be on the same network.
Open up a web-browser on a computer that shares the same networks as the Pi and browse to either http://raspberrypi.local if you are running Occidentalis, or to http://xx.xx.xx.xx where the x's are replaced with your Pi's IP address.
One of the many useful features of the WebIDE is that all of your code will be stored in the cloud over at bitbucket.org. So, before we can go any further, you need to create your free bitbucket account.
Click here to create your free bitbucket account.
Once you have created your account, log into bitbucket and go to your Account page: