I want to change my email settings so that I can send an email from wherever I am. I can only send an email when I'm at home.

If your email account is one from the company that hosts your internet, that is normally how they work.

You should be able to add username and password to the outgoing (SMTP) servers such that it will authenticate and allow you to send when not on your home network. As KiltedTim noted, your email provider should be able to tell you how to set it up.

Contact your email provider for the correct server settings.