Easy.
Get 2 dance / beat cd's exactly the same (track).
Start both together.
Raise both channels on mixer.
Are they in time with each other?
Club / Mobile DJ's work either in 16 beat measures, 32 or 8, depending on the intro if 4/4 time. (1,2,3,4 beats or 1,2,3,4....14,15,16)
Now try counting the beats for the chosen track.
Normally after 8 or 16 beats, a change in the music, be it singing or another instrument is added.
When you count 16 or 8 beats in - on the 1st beat of the next set of 16/8 beats, start the other cd.
For perfect mixing, you may need to adjust the intro with the CUE feature, taking the start of the bass beat right onto the play button start.
Experiment again.
Pitch control will adjust tempo of the cd tracks.
Think of 2 cars racing on the road.
If 1 car is slightly behind (in beat terms) it needs to be 'sped-up'.
Try adjusting in steps of 2-4-6 and 8%, then fine adjust to the . (point percentage).
When you are confident of crossfading in this example - and you can't tell the difference which tune is playing, in effect, you are mixing.
That's when you progress to other different tunes.
Note:
Some tunes are recorded either high or lower in volume. If your mixer can adjust for this (Gain) please do so before you pump up the volume - it will protect your speakers!
Read info on 'clipping' elswhere on the forum threads / search!!!
Have fun