To get an online presence you will need to have access to some form of hosting, a registered domain name as well as the actual website to upload to your hosting server/area. hosting can take the form of a subscribed service to a hosting company (common for small companies and individuals) where the equipment and connectivity are maintained by the hosting company. This is a very simple and hassle free option.
You could host your own server if you have a suitable server which has the required HTTP server software configured and installed and connectivity to a sizeable internet line (ADSL, SDSL, T1 etc).
Unless you have specific needs, the easiest option is to purchase a domain name from a hosting company and have that domain hosted by them. Costs can vary but are in the region of £35-120+ per year.