the little booklet that came with the starter kit has a section titled verify your product on my.arduino.org.
and insert your product code. a long string of numbers. however, when you visit that URL, it just redirects you to this main site. But I can find no links on the main site for registering new products. Is that still possible?
Please report this issue here:
AFAIK the registration site is still not functional and it is not needed to use your board.
It is also mentioned here