Sutty

Sorry I am a nube and am missing something that is probably obvious.... With that said I am attempting to create a collage of passport pictures that are already sized 2X2. The problem I am having is when I open them up the properties show they are 2x2 but when I attempt to paste them into a canvas that I have set at 4X6 it sais the picture is bigger than the canvas?? I know I can reduce it after I paste it in but I am not sure how to make it exactly 2x2 after doing so. I