In general, to apply for a Consular Report of Birth Abroad (CRBA), you must:

• Fill out the appropriate application form;
• Provide supporting documents;
• Pay the appropriate application fee; and
• Schedule an appointment.

Step-by-step application instructions, including information about applications forms, fee payment, required supporting documents and how to submit your application are provided on the Embassy website: https://ca.usembassy.gov/u-s-citizen-services/child-family-matters/