How do I power up my system using a POE Injector?

Connect the power cord to the POE Injector.

Connect a CAT5e / CAT6 LAN cable from a working wall network jack to the In port of the injector.

Connect another CAT5e / CAT6 LAN cable from the Out port of the POE injector to the POE In port of the computer.  The computer should automatically start.