In this scenario there could be several situations:
- You have a registered domain, but you don`t have any hosting
- You have a hosting, but you don`t have a domain
- You have a domain registered with one company and a hosting registered with another company
1. If you don`t have any registered hosting I recommend you Bluehost
I wrote here about how to get started if you have a domain, but you don`t have a hosting so please follow.
2. If you have a hosting, but you don`t have a domain what I would suggest is to register the domain with the company where you have the hosting.
They will automatically set up all the settings that you need.
After you register your domain with them, you will be able to install WordPress.
If you don`t know how to register a domain on your hosting provider please request a tutorial and I will do it for you.
3. If you registered your website`s domain with a company and the hosting with another company what you have to do is change the NAMESERVERS.
This thing depends a lot on each domain provider. I will show bellow how to change nameservers for each Domain provider, but to do this I really need your help.
If you don`t find your domain`s company bellow, contact me, I will create a tutorial and I will post it here so other people like you will have access.