Header Image

Hi Andrew
above codes i have inserted in custom css. but i didnt work.Why?
im sure i used the correct url from the media library. but the image doesnt appear in header. pls help me
thank you
hear are code which i used

header#masthead {
background-image: url(“http://localhost/wordpress/wp-content/uploads/2015/02/everrest-header.jpg”);
}
/* Masthead Background Image */

header#masthead {
background-repeat: no-repeat;
}
/* Masthead Background Image Cover */

header#masthead {
background-repeat: no-repeat;
background-position: center center !important;
background-attachment: fixed;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}