This is the enigma of art, the sacrifice of learning. There is the pain of learning and we feel it because it's inconvenient and constant (teens know this), it changes all of our world view and we out grow things, we change.
Back in the near past, you learned by pouring over manuals and viewing screen shots, then came powerpoint presentations. Today we have those things plus video tutorials. To be able to see the application in action while it's being explained and even being able to open the app and work along side is the clincher. Once you say to yourself,"I think I can do this" you can begin to ask "and how do I do this also?". We have gone from trails of breadcrumbs to trails of loaves. Look on that rock, is that a sandwich and ice tea? In any case, someone has gone before you and prepared a meal for your enjoyment and it's free. There are a number of graphics apps in Linux, these are the big three on my desktop.
Blender 3D is a wonderful though slightly complex modeling and animation program. The Blender web site has instructional videos that are very good. Also checkout the Blender Underground for a start.
GIMP folks can check out Biehl on line tutorials, this is one of many.
Inkscape users can go to Hot Buttered IT
I also have Xara Xtreme and K-3D which have video tutorials too. Videos are great because sometimes describing a workflow with text can be combersome. Seeing what to click and what to expect afterwards clears up a lot of newbie nerves. And you all know what a picture's worth, right? So, at a time when schools aren't teaching what you are interested in, cost are too high, time is limited and professional software way too expensive, you can get for free what you need to learn the tools of the trade. No, Photoshop is not a tool, it is an application. In it there are tools, brushes, vector curves, gradients, fills, strokes, etc., stuff you can also find in GIMP and Inkscape. Learn how to use them for free and transfer that knowledge to Photoshop if you need to. Beats starting from scratch and being in debt at the same time. Think about it, then go for it!!