To create a notification refer this link.
Mostly everything should work perfectly. Suppose if you get the bellow error
Suppressing notification from package com.example.notify by user request then it means that notification is blocked by the Android Framework since the Show notifications check box in Application Manager is unchecked. By default this check box will be checked but there are possibilities that this may get unchecked (I have seen its getting unchecked in one Samsung Nexus S device). Just checking the check box will solve your problem. Show Notifications is available inside Setting->Application Manager ->Downloads->Your Application
Application Manager App
muthumanict 