for what DB is the user? look at this example
mysql> create database databasename;
Query OK, 1 row affected (0.00 sec)
mysql> grant all on databasename.* to cmsuser@localhost identified by 'password';
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
so to return to you question the "%" operator means all computers in your network.
like aspesa shows I'm also sure that you have to create or update a user. look for all your mysql users:
SELECT user,password,host FROM user;
as soon as you got your user set up you should be able to connect like this:
mysql -h localhost -u gmeier -p
hope it helps