How to display data according to first combobox selection by calling WCF from Silverlight

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Silverlight

How to call wcf as I select item from comboboxes.I have to display items in dataGrid according to all combobox selection.
My WCF is like bellow:

[OperationContract]
        public IEnumerable<eventdetail> GetEvents(EventQuery query)
        { 
            return new List<eventdetail>()
            {
                new EventDetail(){  Id=1, Description="Scan Complete:  Threats: 0   Scanned: 1274062   Files/Folders/Drives Omitted: 39",Type= EventType.Error, User="Local Account", Computer="INRG0081", CreationTime=DateTime.Now, EventId="10115", Source="SQL Server"},
                new EventDetail(){  Id=2, Description="Scan Complete:  Threats: 0   Scanned: 1274062   Files/Folders/Drives Omitted: 39",Type= EventType.Error, User="Local Account", Computer="INRG0081", CreationTime=DateTime.Now, EventId="10115", Source="SQL Server"},
               }
}
  public class EventQuery
    {
        public LogType logType { get; set; }
        public EventType Type { get; set; }
        public string Source { get; set; }
        public string EventId { get; set; }
        public DateTime CreationTimeStart { get; set; }
        public DateTime CreationTimeEnd { get; set; }
        public string User { get; set; }
        public string Computer { get; set; }
        public string Description { get; set; }
        public int MaxMatches { get; set; }

    }
 public class EventDetail
    {
        public int Id { get; set; }
        public EventType Type { get; set; }
        public DateTime CreationTime { get; set; }
        public string Source { get; set; }
        public string EventId { get; set; }
        public string User { get; set; }
        public string Computer { get; set; }
        public string Description { get; set; }

    }</eventdetail></eventdetail>

How to achieve that?