I’m not sure I’m clear on your questions, but here goes…
1) To add any application’s icon to the dock in Mac OS X, just drag and drop it there. If you meant how to add this functionality to your application, if you created your application using Xcode, this functionality is already built-in.
2) On how to send http request, you could use the SimpleHTTPServer object. You should visit the Apple Developer Connection and MacDevCenter to see a variety of methods and techniques to integrate the Web, when developing with Cocoa.
3) Any functions or libraries? I assume you meant in reference to Cocoa and http requests? If so, see #2.