Apps How to apply a style/theme?

[Lewis99]

I have an app and would like to set a theme/style. How do i do that?
I know you go into androidmanifest and change them but i made a theme using the website below and if you try it out it downloads many themes, how ca i apply all of them?
THanks

Android Action Bar Style Generator

PLease help, been stuck on tis for a while.