Ohhhhh geeze we have been worrying ourself sick over this problem. We have SMF 2.0.2 Core theme. We know how to change our header, but we having been worrying ourselves sick over trying to change the background colors that would match the header at least some.
How do I get this to work and what do I have to do to get it and get it to work? We are desperate, we do not know anything about coding or anything.
When you download it how do you install in your forum? Through admin install?
Don't worry yourself sick over stuff like this. It's not worth it.
The editor mentioned in the OP here is an online app. You don't download the editor itself. What you do is upload a theme to it, edit the colours, then download the edited theme as a zip. That is then installed to your forum via the admin themes page. If the online editor will give you a result you like, I'd definitely use it. If it wont, you have other options.
Do note that there are already quite a few colour variations of the 1.1.x Core theme, which uses the same images as the 2.0.x version. These are just image and css packs that can be exchanged for the defaults. You could use the images directly in 2.0.x, but the css would stll have to be edited manually, if you chose that route. If you need help with any code edits, people are usually happy to provide advice and/or help.