In system two, it's pretty easy to do things like pick custom colors for everything. Just go to http://www.livejournal.com/customize/ and pick a layout you like and then go down to "change individual settings" and click the button for customizing. There'll be a few different tabs, and you can see where to set different colors and fonts and so on. If you pick a layout that supports it, you can put in a url for an image instead of a color, for the background. One layout that allows for that is "The Boxer", which is the one I'm using here. Another is "Variable Flow", which is what I'm using at judyths.

I pretty much just felt my way along by changing little things, saving, and then seeing how it looked... That's probably the best thing to do. But let me know if you've got any more questions.