Hello, where can I find the MEGA 2560 PRO photoprint
What do you mean by “photoprint”? A pre-existing gerber? You might try the Arduino site for that kind of stuff.
I do not know what it is about, you can explain it to me, how to add it
The templates are in: KiCad’s Project Manager / File / New / Project from Template
I’m not sure though if these templates are always part of a default installation of KiCad.
Also, this is a bare board for a shield. If language is a barrier you could try posting in your native language and see if anybody can get a better idea. My guess is what you really want is here?