Firstly, it's my opinion that you can write a letter to CIC explaining that you had a civil marriage and that you can provide pictures of that day at the court/local office. Provide a notarised copy of the marriage certificate. You may also provide one or more of the below:
1) Joint account statements
2) other joint financial responsibility like a loan or joint utility bills / joint insurance policy.
3) Lease agreement with both your names on it.
4) If you've added each other as beneficiary on the life insurance policy, you can show that
5) Any joint club memberships, invitations to social events etc
6) Pictures of you in social functions, with family etc
7) Any joint travel you might have undertaken
8) Affidavit (Relationship statement) - A notarised document in which you mention the history of your relationship - how you met, how your relationship developed, when you married, your living arrangement, joint financial responsibilities you've taken on, any period of separation etc. This is generally for de facto relationships, you might not have to do this.
Just a guideline, other forum members please comment