I Have a question that REALLY needs answering!

Hi. Im kinda new to all of this but I'm getting along well! :D Well anyways I just had a question. If someone hacks a site and leaves A pic and a few words, how can i find his IP address or other information? ;)

Someone please answer me! :(

Well how do i do that. srry for asking so many questions:| but im talking about a site thats not mine and i dont have any admin access to it

ok thx anyways :( still need help!