Click on the edit selection at the top of the profile. It will let you see many choices of what to edit on the right side of the page. It should list the spouse of your mother or father listed. Under that name there is a selection to edit the marriage. Click on that and it will take you to a page to edit the date and place. Fill in the information and click SAVE. It will appear on both profiles involved. Private profiles are not open for the public to see the edits. You are the only one who can do this.