You can do this as follows;

Give a unique randomly generated identification code (this can be generated from PHP functions like md5 using yours partners email address as input). Now when you submit your text or graphical banner the hyperlink should have of the form


http://yoursitename.com/index.php?ref=parterner's_id

to track the referrer to your referred page should be either PHP or ASP type, when somebody clicks the link the "ref" variable will be passed to your site

Next you have to place the necessary code to store this id