You welcome page might look something like this:
Welcome.jsp:
<jsp:include page="/include/header.jsp" />
<jsp:include page="/include/navigation.jsp" />
<!-- Content of Page -->
<jsp:include page="/include/footer.jsp" />
Think of Welcome.jsp being a refrigerator and the includes being magnets that are on the page.
If you would like to change something in the header.jsp
that would change on every page it is included on, templating in a sense.