Header text

This theme doesn’t come with Custom CSS option, so you have to install a Custom CSS plugin, or create a starter child theme to hold the modification for it.

Use any of this tool to inspect element and its property

Firebug
https://getfirebug.com

Firefox: Inspect Element
https://developer.mozilla.org/en-US/docs/Tools/Page_Inspector

Chrome: developer tools
https://developers.google.com/chrome-developer-tools

In this case, the site title is in #header h1 a

#header h1 a { color: red; }