I am trying to create a login page,which i haven't done before, I have an example that i am suppose to work on and customize it but I am getting all confused, so i was hoping to see if sombody has some good links where I can read a bit more about it, i have searched already...and found something

Actually at the moment, I have a login page,typing username and password logs me in and gets me to a page where I want to be,but what i want to do and understand how it works is that technically I don't know who submits the data, so what I need is help on how to track who is logged in so when they submit that I know it came from them.