Here's my showing how I install a theme. I dunno why but I like how simple it is XD.
If you need any help regarding installing custom themes, tell me.
How I do it:
First I open up MyMenu, then I load my app file (00000072.app, for Wii Version 4.0)
I then open my mym file and start creating the csm file.
If there are more mym files, like my previous Street Fighter theme, I do the same process as I did with DrawnWii. Instead of choosing the name of the created csm file, I rename it to FirstApp.app.
Then, I open up MyMenu again and choose FirstApp.app and the Second csm file. Another file will be created. I name it to SecondApp.app.
After that, I choose SecondApp and the third csm, which will create the last csm file.
Thanks to Kalakoi for helping me with themes like that.