How to merge photos

[RJB44]

I was at the Washington Nationals game this past weekend and took some nice shots of the stadium/field. I have two photos in particular that I would like to know how to merge. They were taken from the same position, just couldn't capture all in view finder, so the alignment should be close. I think with some editing and positioning, this would make a great photo. Just not sure on how to make that happen.