Most things in Eclipse are straightforward *IF* you follow the prompts and read carefully.
1. New -> Project -> Import Existing Project
(Must have a .project file in project root folder, or else create a new one)
2. Server -> New -> tomcat
(Point to your Tomcat installation folder)
3. Servlets don't run in Eclipse, they run in Tomcat or another
J2EE container (e.g:
JBoss)
(Once your project is built and deployed (or published) to your server, they will run in there)
As Bear said, there are plenty of tutorials, examples, walk-throughs, even youtube videos out there.
Search is your friend.
WP