An important, urgent question about classes?

Hi all, I need to learn something about classes in PHP, that I could not understand what's going on really!? For the following sample, what kind of class i need to create? how can i use? For example, I have X students X: from 1 to infinity... With respect to student ID of them, And for each students, I have name,surname,addr,phone,email .... etc.. informations of them.... I want to create a class, such that, i can input info of students, for each student. And for example, when I did this for 10 students, I want to register with "session_register" and add/remove/change registered informarmations. I tried to do, but I could not understand the uses of classes clearly, so I could not do... Thus soem body write me small code which includes a sample class and adding/changing/deleting records for one student inside. Can I register a valuable which is a class? $mydata = new Students(); session_register("mydata"); ? is possible? Do we have any restriction about registering a variable with respect to its type? thanx... best regards...