To import MySQL Database, you must first establish a new database and setup your script to utilise it before you can use a database backup. The database must then be imported:
It's worth noting that phpMyAdmin has various upload and import time constraints. These limitations may prohibit phpMyAdmin from importing the backup in its entirety if you have a big database to import.
Instead, you may use a software like BigDump to get around this. BigDump can break down a large database export into smaller batches and upload them one by one.