应该在您下载的连接器的安装目录中找到该DLL.

最后,在代码中：

using MysqL.Data.MysqLClient;

并且,示例连接：

MysqLConnection connection = new MysqLConnection("Database=database_name;Data Source=server_domain_or_ip;User Id=MysqL_user;Password=MysqL_password");
connection.Open();

MysqLCommand command =  connection.CreateCommand();
command.CommandText = "select * from mytable";
MysqLDataReader reader = command.ExecuteReader();
while (reader.Read())
{
  //reader.GetString(0)
  //reader["column_name"].ToString()
}
reader.Close();