There are a multitude of service providers out there who will host your web page for you, initial costs would depend on the size of the site however where it gets complex is in the bandwidth usage. You will have to sign up for a fixed package which will give you a certain bandwidth at any one time and also daily, weekly and monthly limits. Exceed these and they will temporarilly shut down the site or more likely they will charge you a small fortune.
You will occasionally see this place go down due to exceeding it's bandwidth (usually gloating ABUs and whinging muppets when we've lost) but given the number of users we have, the site runs pretty smoothly which ultimately means Niall is forking out large sums of his own dosh to provide sufficient bandwidth for all except the most extreme muppet influx.
Niall is proud of you and roundly applauds your stupidity.
If that's the advert I'm thinking of then if you click it 300 times, on the 301st you are taken to a different site full of nubile blondes/strapping hunks/mp3s of some great Nelly Paz might like/sheep/fill in your own preference here. Try it Andy it's great