Constant Contact API using php

I have 2 different Interest Categories defined in Constant Contact and would like to use the API to post the information to Constant Contact's API_AddSiteVisitor.jsp script. The provided documentation is pretty vague.

I am trying to post the form data using the following method they suggest(note, this is not the whole script):

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$host = "ccprod.roving.com";
$uri = "roving/wdk/API_AddSiteVisitor.jsp";
$username = "foo";
$password = "bar";

$email = urlencode(strip_tags($_POST['email']));
$category = urlencode(strip_tags('My Category'));

$data = 'loginName=' . $username ;
$data .= '&loginPassword=' . $password ;
$data .= '&ea=' . $email ;


<form method='POST' action='http://$host/$uri?$data' name='form' onSubmit='return checkbae()'>

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When the form is posted my browser prompts me to save the  .jsp file

in their original example file the Form action looked like this which made no sense to me because there is no parameter 'newsletter' defined anywhere else in the script:

<form method='POST' action='index.php?form=newsletter' name='form' onSubmit='return checkbae()'>

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If I paste the url I am trying to post into the browser the email gets added.

http://ccprod.roving.comroving/wdk/API_AddSiteVisitor.jsp?loginName=foo&loginPassword=bar&ea=myemail@domain.com&ic=My+List

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I'd like someone who has actually dealt with this particular application and Constant Contact to answer this for me.

Thanks!