How do I pass parameters in webservice class

public partial class AirSearch : ProviderRequest {
 private string[] selectedAirlinesField;
private JourneyDetail[] journeyDetailsField;[System.Xml.Serialization.XmlArrayAttribute(Order=0)]
      public string[] SelectedAirlines {
          get {
              return this.selectedAirlinesField;
          }
          set {
              this.selectedAirlinesField = value;
              this.RaisePropertyChanged("SelectedAirlines");
          }
      }

 public partial class JourneyDetail : object, System.ComponentModel.INotifyPropertyChanged {
private System.DateTime departureDateTimeField;

       private string departurePointField;

       private bool departurePointIsCityField;

/// <remarks/>
      [System.Xml.Serialization.XmlAttributeAttribute()]
      public System.DateTime DepartureDateTime {
          get {
              return this.departureDateTimeField;
          }
          set {
              this.departureDateTimeField = value;
              this.RaisePropertyChanged("DepartureDateTime");
          }
      }

      /// <remarks/>
      [System.Xml.Serialization.XmlAttributeAttribute()]
      public string DeparturePoint {
          get {
              return this.departurePointField;
          }
          set {
              this.departurePointField = value;
              this.RaisePropertyChanged("DeparturePoint");
          }
      }

      /// <remarks/>
      [System.Xml.Serialization.XmlAttributeAttribute()]
      public bool DeparturePointIsCity {
          get {
              return this.departurePointIsCityField;
          }
          set {
              this.departurePointIsCityField = value;
              this.RaisePropertyChanged("DeparturePointIsCity");
          }
      }