A form will normall have three parts.
the form itself..
<form name="form" action="" method="post">
</form>
An input
<input name="input1" type="text" />
.. and a button to submit the info..
<input type="submit" name="Submit" value="Submit" />
What you do with this information is entirely up to you. You could post it to the same page, or to another one that processes the information.
As said above, it depends on what you want to achieve.