How to make Barley bread?
Experiment more. I'm not a slavish recipe-follower, and while I have the occasional brick when I screw up badly, I have yet to make actually inedible bread in several decades of playing fast and loose with bread recipes. Loaves that were not what I wanted, which I avoided repeating, yes. So bad it went in the garbage rather than be eaten, no.

I would suggest staying a bit on the wet side to give the lower gluten the best odds. 

Perhaps try 1/3 wheat, 2/3 barley and see how you like it. If that doesn't work for you, then 100% barley probably won't either. If it does, 100% might. Only costs a couple of loaves to make the experiments. If the 1/3 wheat does not work to your satisfaction, try half wheat next. Do report back.