binary tree in asp.net

Dear Sir,
 
I want make binary tree in asp.net. which have Parent Node, Left Node and Right Node.
how to view if the left and right child of a parent exist in binary tree.for instance if the left child does not exist how do i show the left child icon is inactive?
If you have code in asp.net with VB.net Or C# with database. Please send me.
I am waiting your reply. 
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