How to put an author-specific photo in the byline?

you can open the content-single.php file . copy and remove the line 33 – 44 then paste this code under line 15.

Add the following code to the style.css file:

.single .author-info {
border: 1px solid #ddd;
margin-top: 10px;
padding: 20px;
min-height: 90px;
}

.single .author-avatar {
float: left;
}

.single .author-description {
margin-left: 110px;
}

.single .author-info h2 {
margin-top: 0;
font-size: 14px;
line-height: 20px;
text-shadow: 0 0 0 #000;
}

.single .author-info .description {
margin-bottom: 0;
}

.single .site-content > .post footer.entry-meta {
border: none;
padding: 0;
margin: 0;
}

Regards,
Dominic