Help with Identifying the Mac with the User in Certain Network

Recently I came into that hacking thing, and of course the first thing I tried, was the aircrack-ng. As far as the cracking is concerned, I didn't managed to do it, because I don't have the computer power to crack it under 2.5 days. So I gave up. But I found out that when I start monitoring the particular network, I can dump certain users using their Mac with aireplay-ng, as well as the whole network. But when I tried this, on my school network (just for fun) I realised that I didn't knew which Mac belongs to which user. And I'm asking for any way to identify the person I'd like to dump. For example, to send them to a webpage, which requests a lot of data and to track the biggest number of data or some social engineering way. (sorry for the bad terminological language (I'm new to this stuff) and for my poor English)