Maybe this is obvious, and I'm just uninformed, but...
Is your webserver a mac, or is your desktop a mac?
If you're talking about MySQL on linux, then there is a package called phpMyAdmin that will let you do pretty much anything you need to in MySQL.
Otherwise, there isn't an app that you run that gives you direct menued access to MySQL. If your hosting provider hasn't given you instructions for accessing MySQL, then [mysql.com...] would be the place to start.