To report misconduct, select extraordinary incident and then the team (or both teams or not sure if required) you need to report it against. Select if the match was abandoned due to the incident and then select add report.
You can then add the details of the incident.
You can then review and submit the report if you're happy to do so, or you can add another incident if needed.
If throughout any of the reporting functionalities you cannot find the offender from the list of registered players, select "offender not here - Input offender name" to manually add the individual and this will then be sent to your County FA to investigate.