My family tree is incorrect. It lists my name then my fathers name and then my great grandfathers name. I need to insert my grandfathers name between my father and great grandfather.
Does your grandfather have a record in Family Tree at all?
If not, first step is to create him as a child of your great-grandparents. If he does have a record already, but does not display as a child of your great-grandparents, use his ID number to add him as a child. Then also make sure his wife is correctly in place, adding her if necessary.
Then copy your father's ID number and add him as a child to your grandfather and grandmother. This will result in him showing with two sets of parents. Go to where he is listed as a child of your great-grandparents. In the box with his name, off to the right side, is a small paper and pencil icon. Click on it. In the flyout window that opens, next to his name will be a link that says "Remove or Replace." Click there and a box will open to confirm that you want to remove him from the family. Make sure the incorrect parents show at the top of that. Click through that box to finish removing him from the wrong parents.
Good luck! Ask for clarification if this doesn't make sense as you work through the process.
Here is an help article which addresses skipped generations which may help.