To use a text field and insert a merge tag: 
1. Create a Text Content area 

2. Click inside of the text area to show text and formatting options

3. Click Merge Tags and select desired merge tag 

***Note: Merge Tags and other personalized information will not show in a test email using Send Test Mail. We suggest if you would like to see how the merge tag will look, create a test list to send to before sending the campaign to your customers.