Hayden Home Banner help

Hi, does anyone know how I could add custom fonts and text to the site title? I have been asked to put a location and persons name underneath the site title in smaller font. They do not have a logo for me to use so I'm required to work with text. 

For example, the site title is now Bethel Baptist Church and underneath that they would like Dr. Royce Smith and an address. 

Website Link - https://bethelbaptistchurchchoctaw.squarespace.com/

Thanks!

add to Home > Design > Custom CSS

h1#siteTitle a:after {
    content: "my name is Tuan";
    display: block;
    font-size: 15px;
    font-family: monospace;
}