Hi there Maria,
I'm no expert [Sandra's just being kind] I just love laking with things
but it is all down too pixels. The lower they are the smaller the image will be in relation to it being worth looking at.
Is it a cheap digital camera, I have a cheap £27 digital, better on inanimate objects than facial shots [all down to pixels] I have it set on large resolutions, and it can reproduce not half bad 8" x 6" desktop background images [photo of the grandson]
Have you got a scanner? If so try scanning a good quality photo, like a school photo of yourself and lake with the photo editing software. If the results are OK then your not a nimrod