You go to "Edit Profile" then click the edit blank section and you'll have the option to change all the colors.
If you add a 'Profile' widget, there should be a drop-down list at the bottom of the edit box where you can change the theme. :)

You can't get what out? The drop down box?
That's very odd, all updated browsers should be working properly. Can you see the drop-down box, just nothing appears?
I don't even know if it's the right box!
Title:
Please read the Widget Information Here! This only works for widgets created for subeta
URL of XML:
It looks like that
That's not the right box, that's why. XD
When you go to edit your profile, click the tab for "Profile" (like mentioned) and then there's a blank box for CSS, and beneath it is a drop-down box for changing colors. (Try looking under your 'Hehe' or 'This doesn't work' tabs, maybe you already have it up.)
it looks like this and click the profile tab