Congratulations boarder428!
Finally the bug has bitten you too. Allow me to enlighten you...
Theme creations in gnome/kde/lxde/xfce/openbox/twm etc etc are all similar. More aptly put they are all same.
You only need to know how to create themes in gnome; and then overnight you can create it/replicate it in kde etc etc.... in minutes, maybe seconds.
To begin with i'd recommend you learn how to use gimp and inkscape.
Gimp does everything. It can create wallpapers, icons, clickable-buttons etc....but inkscape is a vector drawing tool. Which means its always better to use it for making icons and clickable dialogs, radio buttons etc. For widget type fancy buttons, wallpapers and curvy designs and fancy filters you can use gimp... Neways...i dont want to confuse you. Check up this forum for gimp tuts. Check out youtube on videos on gimp and inkscape, download them if need be.
Start with the configuration file .gtkrc which pulls in settings for gnome to assimilate a window...eg: when you click on lets say nautilus file browser icon, apart from system level events .gtkrc calls in various configurations to spawn up a window...
Here is something for your reading:
https://wiki.gnome.org/GnomeArt/Tutorials/GtkThemeshttps://wiki.gnome.org/GnomeArt/Tutoria ... cityThemesFamirialize yourself with terminologies by reading up on them from wikipedia and video howto's from youtube etc:
metacity
mutter
kwin
compiz
qtcurve
.gtkrc
gnome theme engines
kde theme engines
For startup i hope this is helpful...