Default How can I theme my phone app?

Just trying to theme the stock TouchWiz dialer/contacts apk.... How can I do that/learn how to do that, tools I need, etc.? Thanks in advance to any helpful info!
Sprint Galaxy S3 Retired
Sprint Galaxy S4 Retired


Sprint Galaxy S5
ROM: MOAR v1
Kernel: Stock NE5 Kernel
Theme: Click Ui (Nova theme)
Modem: NE5
Apps I NEED: TiBu, Google Now, Beautiful Widgets, Greenify (Donate), Xposed, 8sms, NiLS/NiLS FP


Awesome Collection of Android Apps from XDA Developers!
Collection of Apps for Android Wear (Alphabetized and Categorized)!