Hi Samoz,
If you want to home brew this it would be fairly trivial. I would just use the VisualStateManager. Have 2 states for your "How does it work" pane.
- HowDoIWork_Visible
- HowDoIWork_Hidden
To accomplish the sliding effect you'll need to have the position the pane off the screen. So I would add a TranslateTransform to the RenderTransform property of the pane. Its "X" attribute set would originally be set to the negative width of your pane. For more info see TranslateTransform:
For the HowDoIWork_Visible state set the X property of the TranslateTransform to 0. and the Visibility to "Visible" or the Opacity to "1.0".
Now create the HowDoIWork_Hidden state so you can once again hide the pane. Set the pane's Visibility to "Collapsed" or its Opacity to "0.0". Also set the X property of the TranslateTransform back to the Width.
When the user clicks the Button you just need to call:
VisualStateManager.GoToState("HowDoIWork_Visible");
To hide the pane again:
VisualStateManager.GoToState("HowDoIWork_Hidden");
Other ideas...
You may also be able to adapt the Silverlight Toolkit's Accordion to do what you want:
http://silverlight.codeplex.com/wikipage?title=Silverlight%20Toolkit%20Control%20Overview%20Pg1&referringTitle=Home
If you're not stuck on the sliding in effect the ChildWindow provides an easy way to open up a dialog type view.
http://www.wintellect.com/CS/blogs/jprosise/archive/2009/04/29/silverlight-3-s-new-child-windows.aspx