This is for any restaurant that is on https://livingsocial.com/menus
If you're completely confused by this, here is the safest route:
1) Go to https://livingsocial.com/menus
2) Look for a restaurant you want, and add the items to your cart (ideally, do around $10)
3) When you get to the checkout page, open a new tab in your browser, then go to http://www.livingsocial.com/deals/413928
4) Purchase the voucher for $1, then go back to the restaurant checkout tab. Do a refresh of the page.
5) You should now see a "use this voucher" button. Click it.
6) Check the order total to make sure the vouchers has been applied. If so, order your food.