I'm wondering if this post is in the wrong forum?
Since you have posted in the
servlets forum, the standard way for a client to connect is to enter the web address (URL) of the servlet into their browser (Internet Explorer, Firefox, Safari, ...). An example might be http:8080//localhost/MyApplication/MyServlet
You might also have a web server (Apache / IIS / ...) fronting the web application server, which would enable you to drop the port number, and possibly use URL rewriting to make nicer URLs.
Does that answer your question?
Of course there are many more ways of connecting a client to a server, some using servlets, some without. Without knowing more (as David said) we can't really make guesses.