Complete newbee please help

[Jwise1992]

Hey new to obs my son wants to start steaming and poor old dad has to try and figure it all out please help!!!! he wants to record and stream game footage with the game sounds as well as have a facecam and mic, with the game sounds coming out through headphones but not his voice if that makes sense, we have a pc with obs studio installed what else do we need and how do i set up obs to achieve the above. Anyhelp would be greatly appriciated thankyou