I want to see what the patient will see when they receive a custom campaign text message. How do I do that?

You can send yourself a test text message from your custom campaign in the "Confirm" step of the Campaign Designer. 

If you have included text messages in the custom campaign, you will see the option to "Send Test Text Message" underneath the campaign preview. 

Enter the cell number you'd like to receive the test text message. Then click "Ok."