BEFORE ADDING THEMES MAKE SURE YOU HAVE PRELOADER OR PRIILOADER INSTALLED TO FIX YOUR WII IF IT BRICKS
I don't know how to make themes but with help I found out how to take a theme from any system menu and chage it to the system menu you want it to be.
Here are 4.1 themes that I found, the original wii theme for 4.1 is in the 4.1 theme pack.
4.1U themes (NTSC-U) http://www.mediafire.com/download.php?lwwwkywldlb
Here are 3 Dark Wii Themes for 4.1U. These themes may have to be renamed by adding the .csm or .app extension to the filenames.
4.1E Themes (PAL) http://www.mediafire.com/download.php?lugzkkmjngm
The 4.1 themes in that pack are in .csm format that means they only work on 4.1. to change those you'd need softmii theme converter to change them to myms then the 4.2 app to make them into 4.2 themes.
But the easier way is just grab the myms and use the 4.2 app and make them 4.2 it saves you from having to convert them to myms and then convert back to .csm.
If you have a theme already and it is in .csm format you have to convert it to .mym and then convert back to .csm
Download and use softmii theme converter to change the .csm to a .mym http://www.megaupload.com/?d=DZWP7KQV
Download and use MyMenu to change the .mym back to a .csm for your system menu version
You will have to find and download the 000000XX.app for your system menu.
The original 4.2U wii theme.app http://www.megaupload.com/?d=ZFNWCI64
step 1. open mymenu on your pc
step 2. in the top box of mymenu browse to find your system menu app [00000087(4.2U).app]
step 3. in the bottom box of mymenu browse to find the .mym file
step 4. hit "create my menu"
step 5 wait till it asks you to save it
step 6 save it as whatever you want
Now you have a theme for your system menu.
Then use mymenuify to install your theme on your wii.
Again I did not make any of these themes I found them. I have tryed just about all the 4.1U themes and they all worked fine.
I CANNOT BE HELD RESPONSIBLE FOR BRICKING YOUR WII. BE SURE YOU HAVE BOOTMII (BOOT2/NAND BACKUP) AND/OR PRELOADER TO RECOVER FROM A SEMI/FULL BRICK AS ALWAYS!
I take NO credit for the themes in the 4.1 theme packs.
If I left anything out feel free to add your info. and have fun and I hope you enjoy changing and or adding themes to your wii.