no your database is not in PHPMyAdmin, PHPMyAdmin is a tool that talks to/manipulates databases.
according to
phpMyAdmin its specifically designed to manipulate MySQL databases, although it can export to various formats FROM a MySQL db
if its a web application then its unlikely that you are using Access as a front end tool...
so what are you using to store the data
what language are you using for the front end (the web interface)
I suspect you are probably using PHP in which case you should look do a google search for PHP file upload