Classpath e servlet com pau

Num consigo compilar a servlet de exemplo daqui do guj, olhem os erros:

C:programasHelloServlet.java:2: package javax.servlet does not exist

import javax.servlet.<em>;

^

C:programasHelloServlet.java:3: package javax.servlet.http does not exist

import javax.servlet.http.</em>;

^

C:programasHelloServlet.java:5: cannot resolve symbol

symbol  : class HttpServlet

location: class HelloServlet

public class HelloServlet extends HttpServlet{

^

C:programasHelloServlet.java:6: cannot resolve symbol

symbol  : class HttpServletRequest

location: class HelloServlet

public void doGet(HttpServletRequest request, HttpServletResponse response)

^

C:programasHelloServlet.java:6: cannot resolve symbol

symbol  : class HttpServletResponse

location: class HelloServlet

public void doGet(HttpServletRequest request, HttpServletResponse response)

^

C:programasHelloServlet.java:7: cannot resolve symbol

symbol  : class ServletException

location: class HelloServlet

throws IOException, ServletException {

^

6 errors