<form METHOD="POST" ACTION="https://secure.authorize.net/gateway/transact.dll">
<input TYPE="HIDDEN" NAME="x_Version" VALUE="3.0">
<input TYPE="HIDDEN" NAME="x_Login" VALUE="your login id goes here">
<input TYPE="HIDDEN" NAME="x_Show_Form" VALUE="PAYMENT FORM">
<input TYPE="HIDDEN" NAME="x_Amount" VALUE="amount goes here">
<p><input TYPE="SUBMIT" VALUE="Click here for secure payment form"> </p>
</form>