how to use object of a class into another class in php

[enter [image description here][1]1

enter image description here

I have to classes, first a connect class and then a doLogin class, so I want to use an instance of the connect class into doLogin class but when I want to use it i face much of errors, sometimes it says the mycon variable is not defined or sth... the point is here that I tryed many times to create the instance directly into doLogin class but I couldn't. I highlighted the error location in the image, help me for comming this problem over. thanks!