This will be helpful for some people:
From MySQL command line:
CREATE USER 'newuser'@'localhost' IDENTIFIED BY 'password';
Sadly, at this point newuser has no permissions to do anything with the databases. In fact, if newuser even tries to login (with the password, password), they will not be able to reach the MySQL shell.
Therefore, the first thing to do is to provide the user with access to the information they will need.
GRANT ALL PRIVILEGES ON * . * TO 'newuser'@'localhost';
The asterisks in this command refer to the database and table (respectively) that they can access—this specific command allows to the user to read, edit, execute and perform all tasks across all the databases and tables.
Once you have finalized the permissions that you want to set up for your new users, always be sure to reload all the privileges.
FLUSH PRIVILEGES;
Your changes will now be in effect.
For more information: http://dev.mysql.com/doc/refman/5.6/en/grant.html
If you are not comfortable with the command line then you can use a client like MySQL workbench, Navicat or SQLyog