This is a tutorial ONLY for beginners or for people who don't know how to change their theme.
First you need to look for a theme that you wish to make your StepMania into.
I would suggest going here:
Once you go to that site, click on "THEMES"
Choose any theme that you want and then click it.
Then you click download
Once the file is opened, you open the "THEMES" file first.
Then once the file is opened, it should come to to a named file.
I chose "In The Groove 2" so i came with this.
Now you either extract, copy+paste, or move the file so do either one
Open your StepMania program folder and click "THEMES"
Once you opened it, you now move (or paste) the file inside the themes folder.
Once it's the file is moved (or pasted), then you open up your StepMania.
You now go to "Options" then "Appearance" and then you look for the theme that you have extracted.
Now you select that theme and then you finally have changed your StepMania
I'm still a noob here so i suck at making tutorials.
If you want a video to make it easier then click here: