here's some code that should get you started:

        <igGauge:XamWebRadialGauge x:Name="theGauge" Loaded="theGauge_Loaded" >
            <igGauge:XamWebRadialGauge.Scales>
                <igGauge:RadialGaugeScale StartValue="0" EndValue="100">
                    <igGauge:RadialGaugeScale.Needles>
                        <igGauge:RadialGaugeNeedle Value="0" />
                    </igGauge:RadialGaugeScale.Needles>
                </igGauge:RadialGaugeScale>
            </igGauge:XamWebRadialGauge.Scales>
        </igGauge:XamWebRadialGauge>

        private void theGauge_Loaded(object sender, RoutedEventArgs e)
        {
            DoubleAnimation needleAnimation = new DoubleAnimation();
            needleAnimation.To = 77.0;
            needleAnimation.Duration = TimeSpan.FromSeconds(3.0);
            Storyboard loadedStoryboard = new Storyboard();
            loadedStoryboard.Children.Add(needleAnimation);
            Storyboard.SetTarget(needleAnimation, this.theGauge.Scales[0].Needles[0]);
            Storyboard.SetTargetProperty(needleAnimation, new PropertyPath(RadialGaugeNeedle.ValueProperty));
            loadedStoryboard.Begin();
        }