Restart idevice by removing the app from the app history then relaunching it again, that should fix you're problem
You're both assuming he knows how to equip it in the first place and he has trouble with his device.. As you don't have any equip yet I should think you don't know how to, go to your profile then go to your equipment page and click on the helmet slot. It should appear and there will be a button saying equip.