Connect Database

I bought an old website ~10 years old that's hosted on a Debian server. There's no CPanel, Plesk, but uses Apache, MySQL, PHP and a bit of Perl to generate the website. Everything is done from the commandline. I moved the site to my new server (VPS) that uses Plesk and have uploaded the entire html tree and database, but can't figure out how to connect MySQL to the database. The winning bidder will compare the old server to the new one and solve this database problem so that the website works properly without disrupting all the other websites I run on my server.