@overtips
to change the menu bar you just need to change the colour in the css file.
.navbar-inverse .navbar-inner {
background-color: #1b1b1b;
background-image: -moz-linear-gradient(top, #222222, #111111);
background-image: -webkit-gradient(linear, 0 0, 0 100%, from(#222222), to(#111111));
background-image: -webkit-linear-gradient(top, #222222, #111111);
background-image: -o-linear-gradient(top, #222222, #111111);
background-image: linear-gradient(to bottom, #222222, #111111);
background-repeat: repeat-x;
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ff222222', endColorstr='#ff111111', GradientType=0);
border-color: #252525;
}
Are you looking to get the image in the middle when you are a mobile screen size?
Cheers,
D