One of the important building blocks for your website is a reliable hosting account. Once you have a domain you need a way to serve the content out to visitors and this is what a hosting account does. A host is a server (powerful computer) which stores your files and provides database services. Once you set up the hosting account you are given a unique IP address (that is how information is located on the Internet) that your domain name will be linked to. You will not need to know the workings of how this is done, just that DNS will point your domain name to the correct server address.
Hosting is inexpensive these days for a reliable server running Linux and providing a MySQL database so you can setup a CMS (content management system) like WordPress or Drupal. Using a CMS is by far the best way for most businesses and organizations to have a website that is easy to manage. As your site grows and more users visit your website (thousands per day) upgrading your hosting may be required and your CMS fine tuned for optimal performance, but that is not very common for small businesses.
Most hosting services provide for backups, some are automatic and some are manual. This is very important once you get your website built and pages of content uploaded so you can recover if necessary. I will help you with the specific details, but to begin with learning how to make a backup and recover it is an important task to know the basics of doing.