Write to Nick:
If you would like to contact Nick, you can write to him in care of his agent, here:
106 - 1947 Pendrell Street
There are other addresses for Nick out there, but all fan mail is forwarded to his agent in Canada, so you might as well send it directly there.
If you want an autograph, it's great to include a self-addressed
stamped envelope, but don't use U.S. stamps. They are no good in Canada, so you will be wasting your money.
If you can't get Canadian stamps, buy some IRCs (International Reply Coupons) at the post office.
It takes about $1.50 CAN to send an autograph to the U.S.; 2-3 IRCs should cover it. (It's better to get two of the
lower denomination than one of the higher. Foreign post offices don't always recognize the higher denomination IRC.) Europeans probably need to send 3-4 IRCs.