Hey guys

A quick question for anyone willing to answer.
I have noticed there are other challenges that can be done but in mine they are locked and doesnt say how to unlock them. its for challenges like skill kills etc. is this unlocked through levelling up?

Yea I think you're able to do them ones you reach a certain level. I just got the one where you get XP for playing the different maps a certain amount of times and I just reached 31.