Howdy, information is a bit sparse to give you a full answer. Would be nice to know what you have got the MTP2 hooked up to (what DJ software on the laptop) so we can help you figure out if the output settings are correct.
In general though:
1) Hook up the MTP 2 to the laptop with a USB cable
2) In windows, install the drivers that are recommended for your DJ software
3) In your DJ software, choose the MTP2 as your controller (if necessary)
4) In your DJ software, set your audio to internal mixer and the outputs to master & cue on the MTP2
5) Hook up your controller with two RCA’s to a stereo (aux in is good). Suggestion: do NOT try to loop back the output from your controller to your laptops mic in. If you want to play the master sound through speakers connected to your laptop, it’s better to set the master out in your DJ software to the onboard soundcard
6) Plug in your headphones to the corresponding socket
7) Check master output from the speakers: play a track, set the crossfader to the deck playing, open the channel fader on the playing deck and then (slowly) open the main volume fader
8) Check headphone/cue signal by hitting the (small round) cue button on the playing deck (use the other deck if master sound is still playing with a different track)
If done correctly, you should have master sound from your speakers and the cue sound through your headphones.
Hope that helps