This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Different servlet containers will name the jar file differently. Tomcat uses servlet.jar, but others may name it differently. Either read the documentation for your servlet container, or start poking around inside the jar files until you find the right one.