I am making a holiday card. I keep trying to crop the picture but it appears to big and only 2 out of the three people in the picture appear in the allowed area..How do I crop and size it to fit correctly?? Size is roughly 3.5 x 5.5??

I am trying to make a holiday card. The Front has pictures running up and down the left and right side. In the middle is the rough 3.5 x 5.5 opening that I would like to place the 3 person picture in. Problem is, only two of the three kids in it fit. How do I crop / make it shrink to fit correctly in this opening? I have tried cropping but it still does not size correctly. under crop in edit, what should I do?? Thanks!