Congrats to the young fellow...
Lots of different things to change what you'd done, not that there is anything WRONG per se in what you've got there:
1) spot meter on skin in the shade. Old school and it works.
2) use centre metered...with the dark shirt it would probably get you there with no exposure comp. might need some test exposures to make sure the exposure is ok.
3) use matrix metered with a (+) exposure compensation. Might need some test exposures to make sure the compensation is adequate.
4) use fill flash
Open shade is a great place to make portraits. You might consider moving your subject so the back ground isn't as difficult to work with.
Practice practice practice.
I'm no pro, but I've made plenty of portraits and I love the view from a fast fifty. ƒ4 is a good aperture to work at at the distance you are at, and the shutter speed is reasonable for handheld portraiture so that is all good.
To be completely honest, its a snapshot and I wouldn't be scared to boost it in post (i'm assuming you're collecting RAW files in at least one card slot).
A quick edit - its tough to work with such a small jpg... but I think you've got something workable in the file.