Global "structures" (newbie)

Hi, I'm a beginner in PHP and I want to access some variable all of my php sites. I want to order them in an array, class,... Eg.: User.Name User.Phone General.Info Camera.Type Camera.Class ... What is the most secure and "beautiful" solution for that in PHP? Can I add an array into the $_SESSION variable? Any tutorial on the net? I have found some but they always use only username and userpass. What's in a big project? An exact example would be a big help for me. Thanks!