How to convert wordpress files to database?

[Chris]

A wordpress site consists of
a) the folder containing all the core php files, themes, uploaded images, plugin files, etc.
b) a database containing pages, blog posts, comments, settings, media data, etc.

Moving a wordpress site requires not just transferring all the files but also the entire database.
If the old web designer made a backup of the database, it's most likely a text file ending in .sql

So in order to put the site somewhere, you need to upload all the files and also restore the database from the backup.
The latter you would usually do using phpMyAdmin, a database management web app that's usually accessible after logging into the member's area on the hosting company's website.