Networking is a very, very, very broad term. You might have more luck if you put some limits in your query, such as "I am looking for sample code for socket programming under c#". Still broad, but much more answerable.
C# has a lot of networking functionality built into the .NET framework., mostly in the System.Net namespace. I have found very few things that require using an external library or the windows networking api. You might check out the System.Net namespace and see if it has what you needs, otherwise maybe clarify what you are looking for.