Getting the .NET client up and running
To get the built-in .NET client up and running refer to the assembly and copy the endpoint configuration.
Procedure
SDL Tridion World Article: Using LINQPad with SDL Tridion
SDL Tridion World explains how to connect to the Core Service from LINQPad at this URL: https://www.sdltridionworld.com/articles/sdltridion2011/using_linqpad_with_tridion.aspx.