I would go for photoshop to blur the background or give it an overlay. However you can try giving it a linear gradient on your top-container class before the url call on the background-image as so:

background: linear-gradient( rgba(0,0,0,0.5), rgba(0, 0, 0, 0.5) ),url(../images/background1.jpg) no-repeat center center fixed;

just change the rgba value to what you need. Hope this helps.