You were told already, do you have understanding problems?
Download an injector. Make folder named "Hack" or anything like that. Put .dll file and injector file into the folder. Re-name .dll to the same name as injector, so if injector file is named "AirDropInjectJeez", then you re-name the .dll to "AirDropInjectJeez" too, just adding .dll extension at the end (making it AirDropInjectJeez.dll).
After that, you open the injector and write in Engine or Engine.exe wherever you can enter process name, then start the game uh... Also I think I missed step about making the injector know what .dll to inject, but you only need to use brains and your English knowledge there.