If you'd never made a website-- you probably wouldn't know.xD It's for background/header/footer/ect. colors. For instance, I hate the lightblue color, bc it's not the right hue. So, I go there, click to blue, go to a lighter blueish grey and copy and paste the HTML code into the color thing. Then, it'll be that color!
Well, no, but I do have a MySpace and it's basically the same thing for your profile. But it shows the color you want so..yeah :P
Well...Yeah, most things like Activeboard is horrible. Not many selections on colors, but it DOES have custom to put html codes.
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You pick a color and copy and paste the hex code (example: black = #000000) It's used for HTML and CSS, or one Gimp, if you have a nice color, in the code box you paste your selected hex code into the code box.