Padding a Single Image

This might have been discussed before, but here’s what my code looks like.

/* 2)-=-=-=- Structure -=-=-=- */

#container {
padding-top: 0px;
width: 765px;
margin: 0 auto;
text-align: left;
}

.container_left {
background: url(images/container.gif) repeat-y;
}

.container_right {
background: url(images/container_right.gif) no-repeat top right;
}

.topline {
background: url(images/container_top.gif) no-repeat;
}

#content {
padding-top: 150px;
margin: 20px;
width: 480px;
}

#content_bg {
background: url(images/attempt.gif) repeat-y;
}

/* Uncomment if you want to use the tagline feature (make sure you uncomment h1 above and comment the original h1) – off by default
.tagline {
color: #888;
margin: -18px 0 0 9px;
position: absolute;
font-size: 1em;
}
*/

………………………….

I want to make the image within:

.container_left {
background: url(images/container.gif) repeat-y;
}

NOT show up until 150 pixels down. If I just do the padding thing in CSS.. it tends to put the whole page down another 150 pixels.. as opposed to just this background.

Any help??