Perhaps the SMTheming Wiki put it best when it stated:
Commands are how things get done in the theming world. Without them, you can't really do anything but change graphics, and a number of people have already done that with mixed results.
My own first efforts at theming were similar to yours (and just about everyones') in that I swapped out existing graphics for other ones. Actually, I wrote a narrative about how I learned to theme one time for the Z-i-V forums here:
http://zenius-i-vanisher.com/v5.2/viewthread.php?postid=330593#p330593
I would encourage you to keep theming if it interests you. It's true that educational resources on the topic are a bit scarce, currently, but I'm trying to improve that bit by bit.
In the meantime, some resources do exist. There's...
1. this thread on the Z-i-V forums in which kyzentun, Mad Matt, freem, and I helped a novice make his first theme
2. the SM Theming Wiki has some useful things, though the only part of it I can recommend is
the section on classes of screens because it lays out most of the available Metrics
3. the
example screens bundled with StepMania's source are very thorough but arguably more advanced in their pedagogical style
4. the
bundled Themer Docs have useful, though somewhat disorganized information
Hope this helps get you started. :)
