You have to first login with your Google account or any other And next you have to rotate the rotating bezel (the small circle on the side which can be rotated) of the watch
What is the issue bro? If you are having problems when changing the wallpaper, try the following solutions: 1, reset the smart watch. 2, uninstall and re install Fitpro. 3, Turn on Bluetooth, location and Internet. 4, Try during a different time of the day (server maybe overload).