There is a "select by color" option too which should allow you to globally select all the goldish Inca pattern (for example) with one click and
maybe fiddling with a slider control a bit. After that you can click "cut" then if you want you can then paste what you just cut as a new layer which makes it easier to work on it.
First off I should mention that you should get used to dealing with "layers" in photoshop or similar software. Put everything you can think of it its own layer. Then you can do things like switch off all the other layers to isolate the one you want to work on. This makes things much easier as you go along. Then you can do things like globally tweak the color of a single element without disturbing the rest of your art.
Basically if I was starting at the beginning what I would do is start selecting, cutting and pasting a bunch of individual elements into their own layers. They stack automatically so you can easily see how the whole thing looks any time you want. Once everything is put into several layers, it really eases the rest of the work you need to do. You can even make layers which have lines or whatever on them to use as just guides or whatever, then turn those layers off or delete them come time to print so what you see is what you get. And it just takes a click or two to get there.
In this layering method, what you've done so far can be switched off so you can then deal with the Inca pattern on it's own. And that should be a simple matter of increasing the contrast so it's quite high, then selecting
by color which will be a one-click step to isolating all that pattern with ease. After that, you can go in and clean up any flaws, then globally fill it so it's all whatever uniform color you want it to be or maybe just fiddle with contrast or one of the other filter tools so it looks like you want it too. Once the pattern is complete and looking good, you just create a layer behind the other stuff and make that whole layer a rectangle with your background color and Disco! - your done.
I used photoshop for a while before I built my Linux PC. If you have Linux, there is a very good graphics program which is essentially a clone of photoshop called
Gimp. Both of them have such vast functionality that the learning curve can be a tad steep, but you can do so much with either program that it's worth the effort. If a guy didn't have the money for Photoshop, (or even if you do but just want to try it) I highly recommend Gimp.
Actually, Gimp may have a version which works on Windows - I don't know either way.Looks like you're doing good work so far. Kudos.
edit to add: After looking it up, it looks like Gimp is Linux only.
