I am a beginner in Salesforce and Apex. Can anyone help me write TestClass for this Apex Class.

Event Trigger Handler

public class EventTriggerHandler {

    public static String comma = ',';
    
    public static void AfterInsert(Map<id, Event> EventMap)
    {
        try
        {
            String NameTitle ='';
            String Names;
            
            List<EventRelation>EveRelationList=New List<EventRelation>();
            EveRelationList = [SELECT Id, RelationId,EventId FROM EventRelation WHERE EventId In : eventMap.keyset() and RelationId != null];
             system.debug('AfterInsert count_____'+EveRelationList.size());
            Set<Id> WhoIds = New set<Id>();
            for(EventRelation eveRel : EveRelationList){
                WhoIds.add(eveRel.RelationId);
                system.debug('WhoIds after insert_____'+WhoIds);
            }
            List<Contact> ConList = New List<Contact>();
            ConList=[Select Id,Title,FirstName,LastName, Name FROM Contact WHERE Id In : WhoIds and Title != null and Name != null];
            for(Contact c : ConList){
                if(c.Title!= null)
                {
                    NameTitle = NameTitle+c.Name + '(' + c.Title + ')' + comma ;
                }
            }
            Names = NameTitle.removeEnd(comma);
            System.debug('Names'  + Names);
            List<Event> eventList = new List<Event>();
        
            for (Event e : [select id, Title__c from Event where Id in: eventMap.keyset()])
            {
                e.Title__c = Names;
                eventList.add(e);
            }
            update eventList;
        }
        catch(exception e)
        {
             throw e;    
        }
    }
}

Event Trigger

trigger EventTrigger on Event (before insert, before update, after insert) {
    if (Trigger.IsBefore) {
        if (Trigger.isInsert) {
        }
        if (Trigger.isUpdate) {
        }
    }
    if(Trigger.IsAfter)
    {
        if (Trigger.isInsert) {
            EventTriggerHandler.AfterInsert(trigger.newMap);
        }
    }
    
}