Pass variables into a renderer

New to geocortex. I have a workflow that creates graphics and updates a graphics layer. Ideally I want the user to be able to select from a DisplayForm the Color from a combo  and  Opacity via a textbox (0-1) and be able to generate the renderer on the fly to pass UpdateGraphicsLayer method. 

 

I am just using the sample renderers

 

New ESRI.ArcGIS.Client.SimpleRenderer() With { .Symbol = new ESRI.ArcGIS.Client.Symbols.SimpleFillSymbol() With { .BorderBrush = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Colors.Cyan), .BorderThickness = 1.0, .Fill = new System.Windows.Media.SolidColorBrush(System.Windows.Media.Colors.Blue) With { .Opacity = 0.5 } } }

 

But want to pass the variable graphicsColor (which comes from a list of valid colours) and opacity. I cant seem to escape out and put the variables into the renderer definition. Any suggestions.