The first thing to tell you is that paid accounts have a lot of flexibility. Luckily, free accounts can do nearly as well by using something called "overrides," but these are generally complicated and only available in Style System 1. So, in order to really change the way this LJ looks (I assume this is a free, not paid, account), you'll have to do a couple of things.
Firstly, go here:
If the LJ Style System is already set to S1, then you're good to go. If not, then I need you to make that change.
Next, go to "Modify Journal" and choose an available style that you like. Keep in mind that some styles will not show a background image if you choose to put one in later, or do not offer enough room for the image to be seen properly (it all depends on the image used).
Now, when you scroll down, you will see "Color Themes," followed by two buttons. Choose "Custom Colors." There should also be a list of values, followed by hex codes (#rrggbb). These will determine the colors of the listed LJ parts. Go ahead and enter the codes until it looks however you want it to be. I will state now that this can be an incredibly time-consuming project, as it mostly goes by trial and error until you find "perfection."
Continue to scroll down until you find a text box. This is where the overrides are entered. The thing about overrides is that you generally need to combine them if you have more than one, and you have to enter a specific type of override for the various styles. They can also mess up the appearance of your LJ if they are incorrectly combined or if the wrong type is used. Therefore, this can get rather tricky.
I need you to tell me the journal style you chose and what it is that you want altered: comment links, a background image, font, etc.
I will then post to this with the codes and further instructions.