Here's a step-by-step screenshot tutorial.
Try to follow the steps closely to make the themes work.
Thank you. X
Step 1: Download iFile from Cydia.
Step 2: Find a theme you'd like to download.
Step 3: Click on the download link.
Its usually below the screenshots.
Step 4: Click on Direct Download.
Step 5: Tap on Open in "iFile".
Step 6: After it opens up in iFile, choose unarchiver.
Step 7: After extraction of file, click Done.
Step 8: Tap on Edit.
Step 9: Tap on the theme you want to use.
(Make sure it has a blue folder icon on the left.)
After selecting, tap on the bottom furthest right icon.
Step 10: Cut the file. (Or copy if you want to)
Step 11: Tap on the top left button as seen to go to the first page.
It should show as "/". (Refer to next screenshot below)
Step 12: Once you're here, you'll just have to look for the folder
that you're suppose to paste your theme into.
Different themes have different paths.
List of theme paths:
General Themes: var>stash>themes
Color Keyboards: library>color keyboard>themes
For biteSMS Themes, refer here.
After you have paste the theme(s) you want into final folder,
go to winterboard, select it and respring.
The theme should be installed by now.
If it doesn't, kik me @youtookmylove. Happy theme-ing!