Click the 
on the toolbar until
the virtual record is displayed in the centre
panel.
Hover over the virtual record with the mouse.
Click
on the virtual record and move forwards
and backwards, at any speed, to hear exactly what you would hear
if you applied those same movements to real vinyl.
Use the left mouse button for
normal scratching (non-catch-up
mode).
Use the right mouse button
for catch-up scratching (The record,
when released, will catch up to the would-be playing position).
Tip: The closer you click to the centre of the record, the greater the amount of momentum applied.
Tip: If you want to ascertain the exact deck to scratch, use the Left Shift for Deck A, and Right Shift for Deck B.
You can apply added effects to a scratch such as muting and momentum release variations while scratching. For details on how to apply muting click here. For details on momentum release variations click here.
How to apply muting to a scratch
How to record a scratch sample