Hi Rahul,
I get this error after start-up or when i click tomcat exe's :
I don't get it, how can you get this message after you start-up?
You have to keep in mind that Tomcat as a web-server isn't like a program that open a windows while executing and have a GUI, he is a service and run in the background, you put your web application at the properly folder (under webapps, that is inside the Tomcat folder) and starts it, so if you acces in a browser like IE or Firefox at local host slash context name port 8080 you'll see your web application running.
After you start the tomcat you can see if it's running properly accessing him from a browser in
http://localhost:8080/, it will return you a tomcat default page/admin panel.
And about the books to study i think that there is no better book to learn from zero Servlets and
JSP's that "head first servlets & jsp", if you're not understanding something about the content
you should consider to study some J2SE concepts better before run to this.
Visit and register yourself at
www.BlackBeltFactory.com/ui#!/ref=jmotta (yeah .. using my reference you'll help me to help other people), and do our courses/exams, there will be lots of coachs that want to teach/help you with anything!
Hope it helps you, feel free to ask more questions!