<form method="post" action="http://2captcha.com/in.php?id_constructor=23" enctype="multipart/form-data">
<input type="hidden" name="method" value="post">
Your key:
<input type="text" name="key" value="MYID">
The CAPTCHA file:
<input type="file" name="file">
<input type="submit" value="download and get the ID">
</form>