manual for adding wordpress content to new wordpress installation on subdomain

I have a depricated wordpress site, getting immunify notifications very often that site is not clean. I want to make subdomain with new wordpress installation and built up the site on that new subdomain. I have access to all files, database, dns. I want a manual what to do step by step to get this done. Which directory should be copied from www to newsubdomain, what actions must be made in database (copy) etc. So when all actions are done I have two identical sites, one on www. and one on the subdomain.