Tree and graphes in c#

Question

Hi C# lovers

My question is about Tree and graph in C# 

How to implement such structure, which I will need them to compare depth first search, breadth first search and A* .

I found with google some implementation(http://msdn.microsoft.com/en-US/library/ms379572(v=vs.80).aspx) but they use recursive search and I can't move between nodes?

And why there are no one talk about tree and graph with pointer?

Thank you