It depends on the kind of text you will be adding to the banner. If you want to add text that will be static (as in, it will never or rarely change) and want to add custom fonts, you should probably edit the image in Photoshop.
On the other hand, if the content in the banner will change constantly, then I would suggest adding the image as a background. Your banner h class would look something like this:
.banner_h{
display: block;
width: *actual pixel size of the banner*;
height: *actual pixel size of the banner*;
background: url('*location of file*') no-repeat;
}
If you leave the width to a percentage what will happen is that the div will not have anything inside of it and thus will not show the banner, so you need to figure out what the actual width and height of the banner is and put it in this CSS declaration so that it shows the banner.
Once you have done this, delete the image from the tag and replace it with the content you wish to add.