Vista - Dynamically Drawing Objects

This should be so simple! I need to generate a bar graph using WPF. It's
easy to do with XAML and I have some very nice graphs. But I need to
dynamically genenerate the graphs because I do not know before I query the
database how many bars I will need. It should be so simple to draw as many
rectangles I need and to place them on my canvas. But I can't find anything
on how to do it. What few WPF examples I can find on anyting are written in
C#. Surely there are Visual Basic users out there as well.

OS XP Pro
Language VB 2008

Any ideas will be greatly appreciated

Ken