You would first need to register a domain and purchase hosting for it. The domain registration and hosting can be purchased from most hosts as packages. We don't offer recommendations here but you can get them at https://webhostingtalk.com
Once you have registered the domain they will give you credentials for FTP and the database.
You would first download the phpBB files from here:
Download FTP client like WinSCP which will allow you transfer files from your computer to the host from here:
Unzip the file and uplaod to your host using WinSCP, you will need to enter the credentials provided by host.
Follow the directions here for installing phpBB.You will need the database name, username and password provided by your host during installation process.
https://www.phpbb.com/support/docs/en/3 ... tallation/
“Results! Why, man, I have gotten a lot of results! I have found several thousand things that won’t work.”
Attributed - Thomas Edison