Certificates are created through the Certificate form (which is slightly different from the IndustraForm used as the actual Certificate). You will need to fill out the Certificate Type, Description of work to be done, and also the Valid From and Valid Until dates that control the period of time this certificate is being issued for. See the "Adding a Certificate" screenshot below for more details, and the Certificate Fields table for a complete list of fields and their descriptions.
Once the Certificate has been added, the IndustraForm used for the Certificate will be populated with the data entered.
Certificates are accessible on mobile devices (see the Permit Mobility section).