Your database's endpoint is on its service page under Connection details, with a copy button. The engine — PostgreSQL or MySQL — is the one you chose when you ordered.
The database password is shown exactly once, on the service page just after provisioning. Save it into your password manager there and then — we can't show it again. If you lose it, open a ticket and we'll reset it for you.
Connect with whatever you normally use — psql or mysql on the command line, a GUI client, or your application's connection string. Point it at the endpoint from your service page and authenticate with that password.
We handle the parts that are easy to get wrong: the engine is patched and monitored for you, backups run daily with seven days of retention and point-in-time recovery, and on the Scale plan a second node takes over automatically if the primary fails.