Hi,
You need to install Connector/NET (the MySql ADO.NET driver) explicitely, is not bundled with MySql server.
Having said that, if you install MySql thru the MySql Windows installer, it can download and install for you a bunch of client tools (like Workbench, Connector NET, ODBC, etc.) if you specify so in the installer wizard.
If you tried the standalone installer for Mysql server, then is not installed.
You can check if you have Connector/NET is installed by checking in the GAC, from a VS prompt run the command
gacutil -l mysql.data
If you get results, then you are just missing the reference (be sure to use a .NET target version between 2.0 & 4.5 for your project).
You can get the Connector/NET installer from
http://dev.mysql.com/downloads/connector/net/
Last stable release is 6.5.4, last development release is 6.6.4.