A database stores information, text to be more exact (or links to images etc...)
It doesn't store files, it can store the CONTENT of files, but not files.
If you want people to be able to retrieve information from the database, look up "select statements",
ie:
$query = mysql_query("select * from table_name");
while ($rows = mysql_fetch_array($query))
{
$var = $rows["field_name"];
}
echo $var;
You could then write that all to a file I guess, and then download that, or you can download files directly from the server, the best way to go about that is to go to hotscript.com and grab some of the open source stuff from there, then either use one of those (tip - add security, the one I used to learn from took me 5 mins to crack into and give me access to EVERYTHING on the site!)
Hey, this [ php] stuff if great!