This article can be refer as reference only, how can you build your first Management Agent connect to Service Now. The samples code show how to call the Service Now REST API from ECMA 2.0
The table for users is sys_user in Service Now or get the details of table from service now developer.
Service Now API exchange the information in form of JSON (Java Script Object Notation)
To parse JSON object in C#, use the Newtonsoft JSON library http://www.newtonsoft.com/json
The Code, please make your own adjustment according to your need,