To add new fields to the customer app, the web integration, or to the New Booking form to collect more information from your clients, you must first go to Pricing --> Service Levels, and click on the service level that you wish to add the text field to. 

You can add the same text field to as many service levels as you would like. 

Once you have chosen Service Level, find Ride Input Fields on the left-hand side, and choose the type of input field you wish to add. 

This option will then be presented for that level of service when a ride is booked through the customer app, your website, or by the dispatcher.