Ok, easy one (but not for me...) Where is the file, and what code, should I edit to change the size of the photos. Now the images are displayed smaller then real size.

Well, that would all depend on what exactly you are talking about. You certainly have not said much. Review our "read before posting" post.

Then maybe tell us something about your site. Also check out the theme options tab as it is probably what you are looking for.

Thank you sbillard,
in fact, that is what I know about php: nothing! So I thought that saying what I said would be enough. I really did a search (a long one, believe me), but no response to my question, at least to my level of knowledge. I use ZP integration with WP by tech.einaregilsson.com.
At http://www.barrento.com/wordpress/zenphoto/experiencia1/mochoOrelhas1.jpg.php you can see that my photos are displayed smaller than real size (click on the image to see it bigger). I simple dont know where or what to change. I tried to change printDefaultSizedImage in the zp-image.php file, no luck... I know it would not be hard for someone who knows PHP, but that is not my case.
So I wonder what file and code should I edit to get my photos at their real size. Can you, or someone, please help me on that? Thank you.

You seem to use a custom theme. Please understand that we can't fix your theme for you. Read the theming tutorial and look at the standard themes.

hum, I thought all themes had the same code, just different looks and options...

Themes can be quite different and can use custom code or hardcode fixed image sizes for layout reasons that override any setting (like the stopdesign or zenpage theme do partially). That depends on the theme and what its author wanted to do. Since Zenphoto has also a framework you can even do a theme not using any of the standard template functions.