Solman 7.2 ITSM Enduser incident creation Question

We have solman 7.2. In ITSM for incident creation for the end user we are planing to use the webdynpro application "ags_work_incident_create_app". We have requirement to add custom fields. Is this the right application? Or we should be using copy business role SOLMANREQU and customize using AET. If we use the "ags_work_incident_create_app"

how do we add custom fields?

Thank in advance for the for the help.