If you have any events in your client already, you should be able to export one of these - to an application configuration package - and this will give you an example to work from.
Or you can RMB on the event header and choose export custom event.

this creates a .ins file similar to the one below:

-------------------------------------------------------------------------------------------- -- Export file for Custom Events BAT_BAL_DATE_ALIGN.-- --  Date    Sign    History--  ------  ------  -------------------------------------------------------------  230125  IFSAPP  Export file for task BAT_BAL_DATE_ALIGN.-------------------------------------------------------------------------------------------- SET DEFINE ~PROMPT Register Custom Event "BAT_BAL_DATE_ALIGN"DECLARE   event_lu_name_      VARCHAR2(30)    := 'ShopOrd';   event_id_           VARCHAR2(30)    := Database_SYS.Unistr('BAT_BAL_DATE_ALIGN');   id_                 VARCHAR2(100);   info_msg_           VARCHAR2(32000) := NULL;BEGIN-- Construct Main Message   info_msg_    := Message_SYS.Construct('');   Message_SYS.Add_Attribute(info_msg_, 'EVENT_DESCRIPTION', Database_SYS.Unistr('Need date is changed on a Batch balanced Shop Order'));   Message_SYS.Add_Attribute(info_msg_, 'EVENT_ENABLE', 'FALSE');   Message_SYS.Add_Attribute(info_msg_, 'EVENT_TYPE_DB', 'CUSTOM');   Message_SYS.Add_Attribute(info_msg_, 'EVENT_TABLE_NAME', 'SHOP_ORD_TAB');   Message_SYS.Add_Attribute(info_msg_, 'EVENT_TRIGGER_TYPE_DB', 'BEFORE');   Message_SYS.Add_Attribute(info_msg_, 'MODIFIED_ATTRIBUTES', 'NEED_DATE');   Message_SYS.Add_Attribute(info_msg_, 'NEW_ROW_DB', 'FALSE');   Message_SYS.Add_Attribute(info_msg_, 'MODIFY_ROW_DB', 'TRUE');   Message_SYS.Add_Attribute(info_msg_, 'REMOVE_ROW_DB', 'FALSE');-- Register Custom Event   Fnd_Event_API.Register_Custom_Event(event_lu_name_, event_id_, info_msg_);   -- Register Event Parameter      info_msg_ := Message_SYS.Construct('');      id_  := Database_SYS.Unistr('BALANCE_ID');      Message_SYS.Add_Attribute(info_msg_, 'ID_TYPE', 'NUMBER');      Message_SYS.Add_Attribute(info_msg_, 'PLSQL_METHOD', Database_SYS.Unistr(''));      Message_SYS.Add_Attribute(info_msg_, 'CURRENT_VALUE_DB', 'FALSE');      Message_SYS.Add_Attribute(info_msg_, 'NEW_VALUE_DB', 'TRUE');      Fnd_Event_Parameter_API.Register(event_lu_name_, event_id_, id_, info_msg_);   -- Register Event Parameter      info_msg_ := Message_SYS.Construct('');      id_  := Database_SYS.Unistr('NEED_DATE');      Message_SYS.Add_Attribute(info_msg_, 'ID_TYPE', 'DATE');      Message_SYS.Add_Attribute(info_msg_, 'PLSQL_METHOD', Database_SYS.Unistr(''));      Message_SYS.Add_Attribute(info_msg_, 'CURRENT_VALUE_DB', 'TRUE');      Message_SYS.Add_Attribute(info_msg_, 'NEW_VALUE_DB', 'TRUE');      Fnd_Event_Parameter_API.Register(event_lu_name_, event_id_, id_, info_msg_);   -- Register Event Parameter      info_msg_ := Message_SYS.Construct('');      id_  := Database_SYS.Unistr('ORDER_NO');      Message_SYS.Add_Attribute(info_msg_, 'ID_TYPE', 'STRING');      Message_SYS.Add_Attribute(info_msg_, 'PLSQL_METHOD', Database_SYS.Unistr(''));      Message_SYS.Add_Attribute(info_msg_, 'CURRENT_VALUE_DB', 'TRUE');      Message_SYS.Add_Attribute(info_msg_, 'NEW_VALUE_DB', 'TRUE');      Fnd_Event_Parameter_API.Register(event_lu_name_, event_id_, id_, info_msg_);   -- Register Event Parameter      info_msg_ := Message_SYS.Construct('');      id_  := Database_SYS.Unistr('RELEASE_NO');      Message_SYS.Add_Attribute(info_msg_, 'ID_TYPE', 'STRING');      Message_SYS.Add_Attribute(info_msg_, 'PLSQL_METHOD', Database_SYS.Unistr(''));      Message_SYS.Add_Attribute(info_msg_, 'CURRENT_VALUE_DB', 'TRUE');      Message_SYS.Add_Attribute(info_msg_, 'NEW_VALUE_DB', 'TRUE');      Fnd_Event_Parameter_API.Register(event_lu_name_, event_id_, id_, info_msg_);   -- Register Event Parameter      info_msg_ := Message_SYS.Construct('');      id_  := Database_SYS.Unistr('ROWSTATE');      Message_SYS.Add_Attribute(info_msg_, 'ID_TYPE', 'STRING');      Message_SYS.Add_Attribute(info_msg_, 'PLSQL_METHOD', Database_SYS.Unistr(''));      Message_SYS.Add_Attribute(info_msg_, 'CURRENT_VALUE_DB', 'TRUE');      Message_SYS.Add_Attribute(info_msg_, 'NEW_VALUE_DB', 'TRUE');      Fnd_Event_Parameter_API.Register(event_lu_name_, event_id_, id_, info_msg_);   -- Register Event Parameter      info_msg_ := Message_SYS.Construct('');      id_  := Database_SYS.Unistr('SOURCE');      Message_SYS.Add_Attribute(info_msg_, 'ID_TYPE', 'STRING');      Message_SYS.Add_Attribute(info_msg_, 'PLSQL_METHOD', Database_SYS.Unistr(''));      Message_SYS.Add_Attribute(info_msg_, 'CURRENT_VALUE_DB', 'TRUE');      Message_SYS.Add_Attribute(info_msg_, 'NEW_VALUE_DB', 'TRUE');      Fnd_Event_Parameter_API.Register(event_lu_name_, event_id_, id_, info_msg_);   -- Update all actions with parameters      Fnd_Event_Action_API.Update_Action(event_lu_name_, event_id_, NULL);END;/COMMIT/SET DEFINE &

Great! I didn’t know that. Thanks a lot!