The H-bridge is a circuit used in electronic control of high current devices, particularly where the device polarity may be reversed, e.g. DC motors. The name comes from the fact that the circuit typically looks like a letter "H".
Actually I have a working RepRap now so it isn't all bad, but there are plenty (too many?) guides about what to do to make a RepRap, I thought I'd just point out the problems and mistakes I made building mine.
Video Graphics Array "VGA" is a standard for computer display. It has a lot going for it in the hobby electronics field as it is a pretty simple standard and quite straight forward to implement with sufficient signalling speed, there are also a lot of monitors around to test projects on! Colour is a lot easier to generate on a VGA monitor than on a composite video monitor, but it requires a lot more speed as the frames are more detailed and there are more signals to generate.
The trickiest part of getting Dwarf installed and working, I think, is installing the pk2cmd program, and configuring permissions for the PICKit2 Programmer. This tutorial runs through exactly how I do it on an Ubuntu system, but it should be applicable to most modern Linux distros as there are no Ubuntu specific tools involved here.
DISCLAIMER: This stuff involves altering system files and settings. I am not responsible for things going wrong on your system even if you're following this guide.