Reply to New Computer: Not sure how to activate traktor scratch??

okay i have one macbook pro.. just got a new one with the retina display (looks soooo good).

now i have an s4 with the scratch upgrade.
i know i get the license on two computers.. i've only used it on one.

how do i get my brand new computer up to speed?
how do i get that service center to pull up.

i'm a little clueless and don't want to screw this up.
do i just put in my serial number from the scratch upgrade?
can someone point me in the right direction.. thanks guys!