I’m not entirely sure what you mean by “add my domain and site to WordPress”. You either install WordPress with your domain on your hosting account, or change the address of an existing WordPress site to your new domain.
As I mentioned before, if you can provide your domain in question, I could let you know what are the missing next steps.
To install a fresh WordPress site with your domain:
1) You add your domain to your hosting account. This is something you do in your hosting account and has nothing to do with WordPress. As such, we can’t help you with this step at all.
2) Download the WordPress software to your local computer.
3) Upload the downloaded WordPress file to your hosting account (you may extract the zipped file on your computer before uploading, or upload the zipped file and extract it on your hosting account if your host supports that)
4) Open your domain in the browser and run the WordPress installer. You’ll need the database info from your hosting account to complete the installation.
That’s the gist of it. Detailed instructions are provided here, but you’ll need to adapt even these detailed instructions to your own hosting provider: https://wordpress.org/documentation/article/how-to-install-wordpress/
Also, if you have a WordPress site installed already on a temporary URL but need to change this to your actual domain, that’s a totally different question and you’ll find the official instructions here.
If none of these addresses your actual problem, please provide a detailed explanation of what you’re trying to do — and more importantly — what you’ve done already (as far as your hosting, domain, and WordPress are concerned). And crucially important: please provide the domain name in question.