Replace site title with logo = possible?

Need: replace site title text by a logo OR by a logo + text
I am using a child theme based on 2014 and looking into using your Ridizain instead.
I search different forums on how to replace in Fourteen the site title text with an image of my logo (as I found out, MANY people are having this same request), or even better, change it for the logo followed by some text: generally, solutions propose changes in the header.php file. It partially work, but doing so, the main menu does not stick to the top anymore as a user scrolls down.
Does your theme allows to put a logo, or would you have a solution? I tried to copy the header.php file into my child theme folder and made changes in it, but no good results.