How to arrange text on header

Site URL: https://rabbit-blue-ksfs.squarespace.com

Hi, I am trying to add text underneath my site title in my header. I want the top portion to say "Mackenzie Lark," and then the bottom portion to say "Photography."

The first attachment is what it looks like now, the second is what I am trying to get it to look like. 

The reason the second one looks the way I want is because the template already had it that way, I just can't figure it out on my new one. I hope that makes sense.

I am very very new to this, so please be kind, and I appreciate all of the help. 

Your site is private.

Please set up a site-wide password.

Post the password here.

Adding a site-wide password does not allow anyone to alter your site. It only allows those with the password to see your site. Please read the documentation at the link provided to understand how it works.

We can then take a look at your issue.