To add work item types to a flow:
Click the Work Item Types tab.
Right-click in the Work Item Type Instances table, and then click Add in the shortcut menu.
Click a work item type name in the Work Item Type Selection dialog, and then click OK to add the type to the Work Item Type Instances table.
To display the metadata fields contained within the work item type, double-click the work item type name.
For detailed instructions on adding and configuring work item types, see Adding Work Item Types to a Flow.