1.) make sure you have drivers installed for your product, those can be downloaded from AMD here: https://www.amd.com/en/support .
2.) Once you have a driver installed, simply right click your desktop and click "Display Settings"
3.) Displays that is properly connected should be identified under the "Rearrange your displays" panel.
Simply click the number of the display you want to enable/configure and then scroll down the "Multiple Displays" And change the option from Disconnect this Display to Extend or Duplicate.
4.) If you selected Extend you may then need to drag and the number under "Rearrange your displays" to how its placed physically in front of you, this will allow the mouse to leave the edge of one monitor to another.