I have to disagree with @samanthabarnum in that A. you have to start with color theory and B. if your bad at it you can’t design.
You will, of course, need to learn color theory but it can be learned without basic design concepts. And if you have trouble with it you can get help to understand it better. It does come easier to some than to others just like everything.
Photoshop is a fantastic program but in the end it is just a tool. Just like a pencil. If its complexity interferes with your learning or practicing the concepts of design, if you are focused more on how to use the program than your design the I suggest not starting there.
In fact I would follow @IchtheosaurusRex. Designing starts with brainstorming. Simple blocking out of spaces for pictures and words and content. Quick thumbnail sketches. If you have not used Photoshop, don’t worry about using it for that. 99% of the people I work with in the industry don’t.
For someone who has never had a class a good author of books if your just interested and want to see what it is about is Jim Krause.
And finally remember with the programs and the books everything there is also available to everybody else. So there is no replacement for what your already doing. Keep looking at design. I hope I helped.