It sounds like you're automatically trying to fill a form on a website, submitting it and then showing the result. I would check the website's source to find the relevant field and see what it does on submitting.
It will look something like this:
<form method="get" action="/action.php">
<input type="text" name="field1">
The form's method ("get") identifies if you should do a POST or GET request.
The form's action ("/action.php") will give you the URL to request.
The input's name ("field1") will be the name of the parameter.