TinyMCE Defaulting Family Font.

Hey guys! I am in need of some help from you guys if you don’t mind my asking for some help. I am wondering how to make a family font in my tinymce default? I don’t want to make a default of family font on a entire blog but just inside the tinymce so that if I choose to change to a different family font every now and then but I’d like to make one font to the default.

Currently I believe my default font, as I create a new post says Vendetta but I want to make Comic MS as a default in family font setting only in TINYMCE. How can I do that? Thank you all so much for any help you can give me!