You need to add jar file to build path
right click on project->build path->configure build path->libraries tab ->add external jar
browse it and add it.
after adding also if u not getting same error, then
You must include the jar file in the Deployment Assembly of the Project.
1)select the web project which contains the jsp file
2)select Project tab in the menubar in Eclipse
3)select properties in the drop down menu
4)select Deployment Assembly
5)Add your ojdbc6.jar file in it..