Hi, you can set your images sources from the code by using following code:
myImage.Source = new BitmapImage(new Uri("images/myImage.jpg", UriKind.Relative));
http://knowledge-base.havit.cz/silverlight-wpf/Nastaveni-Image-Source-z-kodu.aspx
If you want to add new images to the screen dynamically, you have to add new Image() class instances to the Children collection of containing element, ie. Canvas.
See http://blogs.silverlight.net/blogs/msnow/archive/2008/06/06/dynamically-loading-and-display-images-in-beta-2.aspx
Robert Haken, Microsoft MVP ASP/ASP.NET, HAVIT, s.r.o., www.havit.cz, http://knowledge-base.havit.cz