Opacity of element

Good mornin.
I would like to eliminate this dark rectangle, which is responsible for the forum header (at the top) and make it 100% transparent (so that when you insert a new image without a background, you can't see what's under it, just the forum background directly.
so... how to delete this dark background?

https://i.imgur.com/hEBpCOj.png

Code:

#punwrap {
width: 1200px;
height: 455px;}

.pun #brdtitle {
    background-image: url("LINK HEADER");
    background-repeat: no-repeat;
    display: block;
    height: 100%;
    min-height: 340px; 
    background-size: 100% 100%;}

And... How to create a code in CSS to transfer link? In html is

Code:

<a href="ADRESS"><img src="IMG ADRESS" alt="TXT"></a>

but... in CSS?

please provide your forum URL

Is this solved??

yes