I dont understand how to navigate the Android sign player ?

You can use a standard USB mouse to make selections. Use the left mouse button to select and the right mouse button to go back to a previous screen. If you connect only a mouse you will need to use the virtual keyboard to type. Alternatively you may connect a USB hub and connect to it a mouse, keyboard and an Ethernet dongle. If you plugged in a standard keyboard to the Android sign player you may use the keyboard’s [HOME] button (if it has one) to go back to the Android sign player home screen.