>I am expecting that there is an equivalent manual way of adding references into a project because what if I am doing all my code without the VS.Net? I mean, I am doing all the code manually using an ordinary notepad.


It never ocurred to me that you may be using notepad.
I have never done this stuff without the IDE but if you are using a project file .csproj it should have a node that looks like this:
(SmtpMailSender is something that I made, not a .net thing)

   Name = "SmtpMailSender"
   AssemblyName = "SmtpMailSender"
   HintPath   "..\..\SmtpMailSender\SmtpMailSender\bin\Debug\SmtpMailSender.dll"
/>


IF you want I can make a quick single form project and send it to you to check out.

Chris