Pretty much all web hosting providers are the same, except for services targetting tech savvy customers (e.g. AWS, Digital Ocean, etc.). (Check out my tutorial on purchasing and setting up VPS and dedicated hosting.)
Go to the provider's web site (e.g. GoDaddy, WordPress.com, etc.).
Select a web hosting plan.
If you have an existing domain name you want to use, at some point you will be asked to enter it. (If you want to use multiple domain names for multiple sites, you will be given an opportunity to set that up later.)
Fill out the form. Pay your bill.
Wait for login details to be sent to you inbox.
Follow the instructions in your "welcome" e-mail.
If you are using an existing domain name, you will be asked to visit your domain name registrar so you can update your domain name record (so it points to your new server). If you signed up for a new domain name using your new web hosting provider, you don't need to update any s name records.