Add a new font

I want to add a new font called "willow". I searched online and found this added to config.js to be the solution:

config.contentsCss = 'fonts.css'; 
config.font_names = 'Willow/willow;' + config.font_names; 

But it doesn't work. Any ideas? I have also tried to use this line in config.js and it doesn't put the Willow name in the font combobox:

config.font_names = 'Arial;Times New Roman;Verdana;Willow';

Here is my full confix.js file

CKEDITOR.editorConfig = function( config )
{
    config.toolbar = 'MyToolbar';

    config.toolbar_MyToolbar =
    [
    
    ['Cut','Copy','Paste','PasteText','PasteFromWord','-', 'SpellChecker', 'Scayt'],
    ['Undo','Redo'],

    ['Bold','Italic','Underline'],
    ['JustifyLeft','JustifyCenter','JustifyRight','JustifyBlock'],
     ['Smiley','SpecialChar'],

    ['Font','FontSize'],
    ['TextColor','Maximize'],
 
    ];
};
config.contentsCss = 'fonts.css'; 
config.font_names = 'Willow/willow;' + config.font_names;