Instructions
Install DB Navigator Plugin via menubar >> Settings >> Plugins >> Available-Tab
Download MySQL jdbc connector from here >> http://www.pc6.com/softview/SoftView_99415.html
Unpack MySQL jdbc connector to a directory of your choice
Restart PHPStorm / WebStorm
Add a DB via menubar >> DB Navigator >> Settings >> Connection-Tab >> Plus-Button
Enter the parameters for your connection (see below for possible entries for a local MySQL DB)
Possible parameters for a local MySQL DB
Name: name of choice (localhost)
Description: additional info of choice (dbname)
Driver Library: path to the .jar file (that is the directory used in step 3)
Driver: your perfered driver (most likely the standard driver will do >> com.mysql.jdbc.Driver)
URL: connection URL with a jdbc reference (e.g.: jdbc:mysql://localhost:3306/)
UserName: the db username (root)
Password: the db password (root)