As you can guess from its name, Wanam Xposed is an Xposed module created by the famous Wanam Lite ROM developer. To customize Galaxy phone using this app requires Xposed Framework and root access on your phone. Also, your phone must be running on Android 4.2 and later.
You can learn more about Xposed Framework and how to install it on your phone from this article. How to install and use Wanam Xposed: Install the Wanam Xposed app from Play Store (assuming that you have already installed Xposed Framework 2.2+ on your phone), then launch the Xposed Installer and go to the “Modules” section. Enable the module by checking the checkbox and Reboot the device. Wanam Xposed module provides too many settings, so it is impossible to discuss all of them in one article. You can get more details and download from Play Store
