How to start a file download using CGI?

I am trying to implement a single HTML Web page at my Web site that performs two actions:

1) Prompt the visitor for their email address and then...

2) Start a download of a specific .ZIP file


I have a form on a Web page (example):

<form
action="https://www.mysite.com/myaccount/cgibin/download.cgi"
method="POST">
<input type="hidden" name="THISPROGRAM" value="DOWNLOAD">

<input type="text" size="30" name="address">
</form>

...and I know enough about CGI/Perl to be dangerous.  The current CGI script
I use can retrieve the email "address" input from this form and use it. This is no problem.  I am fine here.  However, my problem is I don't know how a CGI script can initiate a file transfer, in this case MYPROG.ZIP
located at:   www.mysite.com/pub/myprog.zip to the visitor's browser.

I wish that a form action could run TWO commands at the same time, but I fear that this is not possible, therefore I must initiate the file download/transfer from the cgi script (which I don't know how to do).

Any suggestions and examples would be greatly appreciated.