Use the test gateway to see your payment process from a buyers point of view, you can also adapt this gateway to work for Cash on Delivery
The Test payment gateway is very simple to set up and requires no merchant accounts or 3rd party integration. to set it up simply select Test gateway from the gateway list.
Display name: This is what will be displayed on your checkout page if you have more than one gateway selected for use.
Payment Instructions: This will display to your customer on your transaction results page and in the transaction emails. If you are using this gateway for Cash on Delivery then you can put instructions in here. Same if you were using it to allow people to pay with cheques - you would want to include your account number and any additional details.
Note: the other payment notes will still be displayed (set in the admin section of store settings) this will also appear on your purchase emails to.