Welcome to Wikitree John, Most errors of this nature can be corrected on the edit page. Go to the profile. Across the (almost) top there are several tabs. Choose the one labeled edit. On the right side you will see Edit family, go to Spouses and click on edit marriage to _____. You will be taken to a page where you can edit this information. Remember to click the large SAVE button.
There are lots of changes you can make on the edit page, take a good look around. If you need directions, check out the Help Page