My father was married, but not to my mother. How do I fix this on my family tree?
It is not clear from your question exactly what you need to fix.
You can add your mother to the tree even though she was not married to your father.
You can add a wife to your father even though she was not your mother.
If you need help with either of these please post.
Yes, I need help. I'm not very good with this stuff and I don't want to offend any of his family by saying my mother was his wife.
If both parents are in the system then they will display with the father above the mother. There is a little box to the right as you can see in the following example.
If you click the box, you can add a marriage event. Whilst in your case, you could simply leave this blank, given your concern, you could enter Unmarried as either the date or place so there can be no confusion. The system does not like it - hence the exclamation mark in the example above, but it will not reject it.
Alternatively. when adding a marriage event, you can click on the type of event which gives you the following options
However, none of these might fit your situation.
Here is a link to the knowledge article in the Help Center to go with the above post.
At the bottom of the knowledge article are links to other ones that may more closely match what you are looking for.
Also, if your mother and father are still living, you are the only one who can see their information for privacy purposes.