I have no idea if you are trying to connect to a remote MySQL server or one running locally on your machine. Information like that is helpful! So, here's the rundown on how to achieve either working correctly:
If you are running the MySQL server locally (meaning the machine you are using MySQL administrator on is the same one that is running the server), you want to put "127.0.0.1" into the server host field. The default port that MySQL uses is 3306 - so unless you have changed that, it should work.
If you are running the MySQL server remotely (meaning the machine you are using MySQL administrator on is NOT the same one that is running the server), you want to put the IP of the host machine into the server host field. You will have to log in at the command line like you would normally and use the following commands:
mysql> update db set Host='your_ip' where Db='your_db_name';
mysql> update user set Host='your_ip' where user='your_user_name';
You should replace 'your_ip' with your MySQL administrator machine's IP (like '188.8.131.52') and do the same with your database name and username. This allows sets up the permission for remote connecting securely. You would need to repeat this for all machines and users that would be connecting remotely.
Aside from that, you may also have to expose port 3306 on the host machine's router, firewall, etc. Post another question if you need help with that and provide information about operating system, firewall software, and router manufacturer.