Here we go.
Take a look at all of the order statuses available to you by default.
Let's have a look at any one among them in detail. Click on the edit icon next to one of the statuses.
Here is an explanation. As you can see, I have selected the Awaiting cheque payment status. I could, if I wanted to, browse to find a graphic to represent that status. I can see that the highlighted color, when an order has this status, will be royal blue. The next four checkboxes give you options related to the customer. Probably the most interesting option is the Template option. This defines the e-mail template used to send a message to the customer when an order reaches this state.
Click on the little eye icon to view the e-mail that the customer would receive.
Go back to the list when you're done.
In the unlikely event that you do not have enough status options, click on Add new and you will see the same form we were just looking at. Fill it out to match...