Is it posible to add marriage dates?

Edit Profile>Relationships

Click on the profile that you want to edit either in the tree or the results of a search. You should see an area in the UI with "View Tree", "Edit Profile" and "More Actions". Click on the "Edit Profile" link, next click on the "Relationships" tab. Here you can enter marriage dates, marriage locations and divorce status etc.

Thank you very much Randy, that was very helpful!