Custom Payment Gateway Create How?

Hello friends!
I’m very beginner to script modification. So please support to create my Local Payment Gateway in to my Auction website.

Local Payment Gateway Knowledgebase
https://support.payhere.lk/shopping-cart-plugins/payhere-plugins

I have followed below instructions, but I have failed when the second step.
http://www.premiumpress.com/docs/#hooks_paymentgateways

1st Step Done correctly – function.php
2nd Step Failed (where could I paste this code?) example.php
3rd step will do (where could I paste this code?) example-2.php

‘<‘ Occurred syntax error.. with this code..

 function gateway_example($data){  
    
    /* DATA AVAILABLE
   
	$GLOBALS['total'] 	 
	$GLOBALS['subtotal'] 	 
	$GLOBALS['shipping'] 	 
	$GLOBALS['tax'] 		 
	$GLOBALS['discount'] 	 
	$GLOBALS['items'] 		 
	$GLOBALS['orderid'] 	 
	$GLOBALS['description'] 
    
    // shopping cart
    $GLOBALS['global_cart_data'] <-- array 
    
    */

    < FORM METHOD="POST" ACTION="" name="example_gateway">
    < INPUT TYPE="HIDDEN" NAME="ButtonAction" VALUE="checkout">
    < INPUT TYPE="HIDDEN" NAME="custom" VALUE="">
    < INPUT TYPE="HIDDEN" NAME="total" VALUE="">
    < BUTTON TYPE="submit">Process Payment< /BUTTON>
    < /FORM>
    
     }    

Appreciate! Thanks!