First, you need a domain name like www.mybusiness.com. You can buy these pretty much anywhere with prices ranging from $5.95 to over $20. If you buy the name from the place you have host your website (service provider), they will typically provide the domain name free, for as long as you use their hosting services. By the way, it's actually included, not free. Once you have a domain, your website must then be placed on a special computer called a 'server' which is connected to the Internet.
If you have used mainstream technology to build your website you will be able to host it just about anywhere. Assuming you are a small to medium size business without a lot of technological know how to establish, run and maintain you own servers, you will probably 'fit' just fine on a shared server account with one of the thousands of firms offering this service. The great thing about doing this is that you can typically upgrade your service level as your traffic warrants and receive full credit for the remaining time on any account. Most service providers provide various plans up to and including having your own server that they buy, service and maintain.
Entry level hosting will generally start around 6.95 month and increase to something in the area of $99.95 a month for your own server. You absolutely must shop around, taking your website's future potential into account, to come up with a service provider that will meet your needs now and in the future. A lot of developers, myself included, will rent a 'block' of space from a service provider where they will host their client's websites. You should view this option as just another provider. I pay no hosting fees for this website because my clients have already paid for the space.