ok I'll bite.
Assuming nothing is broken (did you use force at any time? These things should fairly drop together...) just slow down and pay attention to what you're doing.
won't lock into place... hmm... does that mean the 'bolt head' isn't rotating into full lock-up when the bolt carrier group is slid into the upper assembly?
gosh, this is tough to diagnose without pics.... send pics? A better description of what the problem is?
....and then there's youtube, how much you wanna bet the answer is in there. once you find out what the problem was please post what it was here, thanks in advance!