One simple approach can be:

<igCA:XamChart x:Name="xamChart" Loaded="xamChart_Loaded">

            <igCA:XamChart.Series>

                <igCA:Series x:Name="BarSeries" ChartType="Bar" DataMapping="Label=Label;Value=Value;ToolTip=Value">                   

                </igCA:Series>

            </igCA:XamChart.Series>

        </igCA:XamChart>

...

    public partial class Window1 : Window

    {

        public Window1()

        {

            InitializeComponent();

        }

        private void xamChart_Loaded(object sender, RoutedEventArgs e)

        {

            ObservableCollection<Data> collection = new ObservableCollection<Data>();

            collection.Add(new Data("a", 5));

            collection.Add(new Data("b", 15));

            collection.Add(new Data("c", 10));

            collection.Add(new Data("d", 20));

            this.BarSeries.DataSource = collection;

        }

        public class Data

        {

            public Data(string label, double value)

            {

                this.Label = label;

                this.Value = value;

            }

            public string Label { get; set; }

            public double Value { get; set; }

        }

    }