awful newbie question

I'm one of the ignorant multitude beginning to grope their way across the threshhold of web programming. I come from another world, not computer science, and thus have a question so basic I haven't found any reference to it anywhere. It's killing me. In the php statement $q->qzml(); what is the symbol '->' called? What does it mean? A php script with this line in it, in which $q is an object and qzml() is a function, returns the error message "undefined function". When I remove this line, the function qzml() is recognized. I have also come across the symbol '=>'. I assume it is not the same symbol. What is it, and what does it mean? Any help would be greatly appreciated. Thanks, -Paul