zyara

To make more clear this changes should be done in your theme header.php.

Extra tips:
You can hide the title and description text from your image header by editing your theme style.css by adding display:none; to H1 and description as follow:

h1 {display:none;
font-size: 4em;
text-align: center;
}

#headerimg .description {display:none;
font-size: 1.2em;
text-align: center;
}