- you configure the servlet in your web.xml
- you properly deploy your application
- you start the server
- you open a browser and navigate to whatever url pattern you mapped the servlet to
If at any of these points you want to reply and ask "but how do I do that" - forget it. If you don't know, you need to read at least a basic servlet introductory article and the manual of your server. Perhaps you want to start with something simpler than Weblogic, such as Apache Tomcat, to get your first simple web stuff to work. Most beginner articles you can find online will focus on Tomcat.