Choose your build target (Win32 or x64). This is important. Since PocketKnife is a context menu extension, you must use the correct version for your operating system.
Build the solution.
Using it.
Copy the Pocketknife.dll to a directory not in your project.
Open a command prompt (with administrative privileges) and type regsvr32 -s pocketknife.dll
That's it. Right click on a folder in the Windows explorer and you should see the context menu options.