You need to look at Jetty or Tomcat which are packaged (separately) with Jboss as the servlet container.
Read a J2EE tutorial on the web - there are many.
Package you servlet into a .war file (the tutorial shouls explain what this is).
copy the .war file to the JBoss deploy/ directory. It will be noticed and deployed (whether you use Jetty OR Tomcat).
Don't worry about webcontainers - just get yourself a .war and copy it into deploy/.