Without setting up your hosting account, you can't do anything with it. So, check out Set up your account.
After setting up your hosting account, you need to get your website's files on it. There are a number of ways to do this, including using the application you used to build your website and using an FTP client.
You probably only need to use one of these articles.
Once you have your website uploaded, check it out using Preview DNS. For more information, see Preview your website.
If you don't see your website (oh no!), make sure you have an "index file." For more information, see What file displays when someone browses to my domain name?
To see if you have a default file, open up your FTP client/website application and make sure you have one of the files listed in the top level of your hosting account, also known as "the root."
Depending on how you configured your hosting account, your website might already be live. Check it out by going to your domain name.
If it's not live, you probably need to update your DNS. For more information, see Change nameservers for my domains.