Simple recording of DJ set in cu base AI

I have just purchased the Steinberg UR 22 audio interface, I am by no means Deadmau5 lol, but I would like some help with this. When I turn on the interface cubase can see the VST instrument fine but when I start mixing it looks like it is only using one channel, all the videos I have watched are always about guitars, drums and singing. I have my Numark mixer connected to the interface and to my laptop but basically its as far as I have got, this is totally a hobby for me and eventually would maybe down the road i would like trying to make music, but for now recording my sets is all i want to do, can someone please help me, I think i am just missing something in my set up, thank you in advance, cheers