PHP GURUS can only help my problem

I’ve been working with PHP and MySQL for a year now.

I’m trying to achieve a small thing which I can’t remember how to do.

I want a user to see a grid (image file) and each pixels clicked stores it in memory using coords. What I want to do is get the coords of all the pixels clicked on another page and inserted into a text box ready to be sent using
mail() function.

Can anyone help me PLZ! Thanks in advance!