Hi there,

you should set it in header.php manually if you wish to set an "alt" attribute and specify the size also. More info about this can be found by performing a web search since it's basic HTML though.

Regards 

djwd

This actually goes beyond regular support. Anyway search for this string in header.php and just add the alt attribute at the end, as such:

<img src="<?php echo of_get_option('pm_logo'); ?>" width="<?php echo $width; ?>" height="<?php echo $height; ?>" alt="<?php echo esc_attr( get_bloginfo( 'name', 'display' ) ); ?> alt="HERE GOES YOUR ALT CONTENT"/>

Hope it helps

Regards
djwd