I have written a simple JSF application using Netbeans IDE. It works when I run using the IDE. But after creating the WAR file and i deployed it on apache-tomcat-6.0.16\webapps. It Gives an error as below mentioned.
org.apache.jasper.JasperException: An exception occurred processing JSP page /login.jsp at line 17
Since there is a JSF class in the stack trace (that is trying to find the FaceContext) I think that the point Cesar made is not the issue. But you should still check that the libraries he mentioned are present of course!
But you say that the error is shown right after the war is deployed. Are you sure? It looks like the error is actually shown WHEN you try to go to login.jsp. So if that is the case be sure to include all the necessary information when describing your problem from now on.
If the FacesContext is not found maybe there was already a problem in the deployment and there might be a more important error message in the logs at the deployment stage! In that case the error is probably in catalina.log