Adding web reference in class library

1. Right click ‘References’ folder under class library project (there is no Add Web Reference option) instead select ‘Add Service Refrence’ 
   
2. In Add Service Reference window click Advanced… button 
   
3. in Service Reference Setting Window click Add Web Reference button 
   
4. Now you are landing on regular .NET 2.0 Add Web Reference window and you can provide a web service URL to be added to your class library.

by adding web reference and from now on you can see ‘Add Web Reference’ option in the right click context menu of Reference folder

and also Visual studio will create a Web References folder under your class library.