[SOLVED] Pass Field Values in a Custom Button

Hi Everyone

Sorry if this has been asked before, but my searches don't find what I was looking for...

I need to pass parameters when click on a "custom button" in a list to open a new php page with parameters
eg:

phpfilename.php?id = fieldid&lastname = fieldlastname&firstname = fieldfirstname

I have try this in the client before in the custom button
window.location.href = "badgefromlist.php";

which work and open the php file, but I have NO idea how to get the values from the list to pass as parameters

Any advice please....

Thanks, appreciate