Calculating time using javascript and automaticailly submitting form to the server

THIS IS A DISCUSSION. I am creating a quiz application, using php. The quiz run for 12 minutes. I want my application to be able to detect when a user login and start calculating the time, immediately it is 12 minutes I want the form to submit automatically if the user is not done. I know i can not do this with php because it server side but i can archive this with javascript and i am not a pro in javascript. Can someone please direct me on how to go about this or point me to the right tutorial. Please. (I hope my question is clear enough)?