How to change body font family

Hi, I want to change body font family name Eras Demi ITC Regular (.tff file) what should I do?

https://drive.google.com/open?id=0B7Z0yWK8oeJMYU41RUV1RjRBSjgwc0ZDUF9oMWhZYTdHbE5F

Hello Saowalak,

Please check this extensive article:

Please feel free to ask any other questions that you might have.

Kind Regards, Roman.