For the area, I don't have any magic tricks for you, sorry. You'll just need to copy one stripe at a time from further down his chest, move and rotate it into position, then mask it in, and lighten it as needed. It'll be very painstaking.
Oh Alrons, please don't wait any longer to take The Raw Class. Your SOOR is nowhere near as good as it should be. Monitor calibration is no longer a requirement, if that's what was holding you back.
Clipping means "linking" layers, in a way. If you clip a layer to another layer below it, the top layer will only be visible where the bottom layer is also visible. Where the bottom layer is transparent, none of the top layer will show either.
Clipping is done (for you on Photoshop on a PC) by pressing Ctrl Alt G.