Posting Smart keyboard theme to Google play

Hi ! I love smart keyboard that I can change themes... but there's was no theme with pastel color and my favorite hello kitty theme..
so I start to make themes myself. I have several themes for girl(most with pastel color and hello kitty themes. ...)
I like to share those theme in Goolge play store and I think i have to post in APK form. however all my theme is in zip files.
Is there any way to post those theme in Goolge play in apk form...?? how to convert it to apk form??
anybody know?? please help!!!!!