New to GameEx Theme creation

Hey, hope you don't mind this lazy post, but I don't feel like trawling through tons of posts to find the answer.

I'd like to create a new 1080 theme for GameEx- while i totally appreciate all the hard work gone into the existing themes, none of the 1080 ones seem to do it for me. I want something elegant and useful created with a designer's eye that is not branded or based on a custom game, something that features big screenshots and logos and is quick to navigate (some of the new themes have flashes or 'please wait' between screens now slowing it all down).

So i'd like to contribute to the community, but want an idea of how fiddly it is to make one (assuming graphics are the easy part). What good links or tutorials exist in theme making so i can spit one out with the aesthetic I prefer? The other issue is my htpc has GameEx on it and it's not the same machine as my graphics design station and I'd rather not install GameEx on my work machine and dont wanna go back and forth 100 times when testing the theme. I dont have a ton of time to spend on this, but am confident I can make a good looking useful theme if it's not a major pain to skin.

any hints for a first time theme maker? Thanks