Emily,
Note: Screenshots of code are sometimes tough to follow along with. It's typically more helpful to copy and paste the actual text of your code and format it real fancy with the {} Code button. But on with your question:
If your images are all the same size, creating a montage is easy. Just treat each image as a matrix and concatenate them into one larger matrix like this:
I = imread('football.jpg');
% Concatenate the images:
Im = [I I I;
I I I];
image(Im)
axis image off
