Compilation Error: The type or namespace name 'Newtonsoft' could not be found

When running this page: http://www.glowfishtw.com/DAAPI/default.aspx

I am getting the error:
 Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS0246: The type or namespace name 'Newtonsoft' could not be found (are you missing a using directive or an assembly reference?)
Source Error:

Line 11: //You need these for JSON parsing.
Line 12: //The DLL needs to be in your bin directory
Line 13: using Newtonsoft.Json;
Line 14: using Newtonsoft.Json.Linq;
Line 15:
Source File: d:\hshome\elliottb\glowfishtw.com\DAAPI\Default.aspx.cs    Line: 13

Is this something that I need to have installed on my server before I can run the page?