getting custom forms to process by running a php script

I am trying to process a simple login form that uses my own wp database table (participants). I have the login page with:

<form action="dologin" method="post" >
        .... table with input fields for username and password ...
        </form>

I then have a page dologin that uses as a template the file template-dologin.php. How can I set up the form to pass the input arguments to my dologin process?

I is currently trying to run …./login/dologin instead of …/dologin

Thanks/Hal