This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
It means that you are not implemented doGet(request,response) in your servlet.
The default method for html form is Get and Not Post.Hence the servlet is looking for doGet method and not for doPost. and one more thing to note is,the service method,looks the http method and calls that method in servlet.In this case it is Get and hence it calls doGet method.