You are brought a receipt, which shows suggested tips for 18% and 20%. Being a party of 5 not using the DDE card, what you tip is at your discretion.
You write Cash on the tip line and either hand the cash immediately to your server (especially if you need change) or just leave it on the table.
There are many tipping threads on the DDP board which discuss tipping in more detail. (How to budget, etc) I found a few links from the first two pages, just in case you want to research it more.