How can I get the output I just mentioned below?

class ModelItem
{
    public DateTime EventDate;
    public int ScheduledEventId;

    public ModelItem(DateTime date, int id)
    {
        EventDate = date;
        ScheduledEventId = id;
    }
}

public string GetEventStr()
{
    List<ModelItem> Model = new List<ModelItem>();
    Model.Add(new ModelItem(new DateTime(2016, 1, 1), 1));
    Model.Add(new ModelItem(new DateTime(2016, 1, 2), 2));
    Model.Add(new ModelItem(new DateTime(2016, 1, 3), 3));
    Model.Add(new ModelItem(new DateTime(2016, 3, 1), 1));
    Model.Add(new ModelItem(new DateTime(2016, 3, 2), 2));

    StringBuilder sb = new StringBuilder();

    int currentMonth = 0;
    bool isFirst = true;
    foreach (var item in Model)
    {
        if (item.EventDate.Month != currentMonth)
        {
            if (isFirst)
                isFirst = false;
            else
                sb.AppendLine("<br />");

            sb.AppendLine(item.EventDate.ToString("MMMM") + "<br />");

            currentMonth = item.EventDate.Month;
        }

        sb.AppendLine("Event" + item.ScheduledEventId + "<br />");
    }

    return sb.ToString();
}