Hi kabayan! 
Your phone must be connected to your PC and in debug mode before you execute the adb.
In the folder where you extracted YMFrontCamADB.zip, there is an adb.exe in there. You can open command prompt, cd to that directory and execute the whole command:
adb logcat | find "FrontFacingCamera"
Your phone must be connected to your PC and in debug mode before you execute the adb.
In the folder where you extracted YMFrontCamADB.zip, there is an adb.exe in there. You can open command prompt, cd to that directory and execute the whole command:
adb logcat | find "FrontFacingCamera"