You need to find someone who can legally use marijuana first.
Then you need to both fill our form D.
Form D: Application for Licence to Produce Marihuana by a Designated Person - Medical Use of Marihuana - Health Canada

You cannot start growing until you get your paperwork....you cannot sell/give any pot to anyone but your designated mma patient.

I think you can grow for up to 4 people...but I could be wrong on that one, I never really looked into this too closely.

It doesn't matter how you find you medical user, as long as they have their license....Just make sure they have a VALID licence.... The old "I thought he had his licence" doesnt fly in court.....

Oh and you need to have a clean record for 10yrs....