You can use the voucher to buy another person flight ticket, or he can go to any ticket counter but you have to be present at the moment of buying the ticket.
Since the coupon has your name written on it, and it is not an anonymous discount coupon, it is valid only if you use it. You could buy a ticket with it, then transfer it to your friends name, but the fee to change the ticket name would probably defeat the point of using the coupon.
You will not be able to transfer the coupon to your friend. Sorry.