Scan in a serial number into info table

Hi Guys,

I'm a beginner with ThingWorx, and have an application where an operator scans in a serial number of a device in need of service, and that number populates a serial number field on a current mashup which then follows the repair ticket through it's process.

Any ideas on how I should start this development?  At the moment there is a drop down picker which populates a required service.  Each service has it's own serial number code which automatically fills in that field and cannot be edited.  I would like the have the user select a " repair " option which will then allow them to scan in a serial number which will populate the serial number field. 

Thanks,