The pc you have the service hosted on must be forward facing if you wish to reach it over the internet. By forward facing I mean the PC is exposed to the internet and has and IP address, etc.
If, however, you are just trying to view the webservices from other pcs on your internal network, you just have to do http://<machinename>/helloworld.wsdl
Take care when facing a pc outwards onto the internet because it is now exposed to the internet; take all necessary security percautions.
I will only tell you how to do it, not do it for you.
Unless, of course, you want to hire me to do work for you.
Read this if you want to know how to get a correct reply for your question:
^^Took that from planoie's profile^^
^^Modified text taken from gbianchi profile^^