1), Make sure PC and Android Phone are in the SAME WiFi network, turn on Android Phone's WiFi.You can use android phone as portable hotspot, and PC/Mac connect to it.
2), Download WiFi Mouse desktop program with PC from: http://www.necta.us.
3), Install Mouse Server on PC, then Run it.
4), Run Wifi Mouse on Android Phone, then click "AutoConnect", or input IP address of PC and click "Connect".
5), Now you are able to control PC. rotate Android Phone to Right to get full keyboard screen, or to Left to get full trackpad screen.
6), In order to re-connect, turn the device upside down.