I am not sure of the compatibility between versions 3 and 4 but you can try. Once you have your database created, from phpmyadmin view that empty database then click on the link that says SQL or Query. On that page you should have the option of uploading a file to import into the database.
If the .sql file is over 2mb you will need either split it up and restore the database piece by piece or do it though the command line if you have ssh access.