To create a dynamic New Relic dashboard using Terraform and JSON templates, start by building a row of widgets with a template file, then define input configuration for the services to be displayed. Dynamically generate rows for each service using template syntax, including calculating the layout and metrics based on the index of the item in the list. Use string interpolation to make the dashboard values dynamic and reusable. Create a Terraform resource to render the output of the template file, apply the configuration, and debug any errors that occur during creation. The resulting dashboard will display rows of widgets for each API service, with dynamically generated metrics and layout based on the input configuration.