URL images in CSS

Hi, I have been trying to install lightbox on my website and im having some problems linking the images.

I think it has something to do with the context of where the images are stored, which won't work on my site because im using a CMS.

So here is the orginal section:
#prevLink, #nextLink{ width: 49%; height: 100%; background-image: url(data:image/gif;base64,AAAA); /* Trick IE into showing hover */ display: block; }
#prevLink { left: 0; float: left;}
#nextLink { right: 0; float: right;}
#prevLink:hover, #prevLink:visited:hover { background: url(../images/prevlabel.gif) left 15% no-repeat; }
#nextLink:hover, #nextLink:visited:hover { background: url(../images/nextlabel.gif) right 15% no-repeat; }

I changed both the prevlabel.gif and nextlabel.gif so it was pointed at a specefic place like this:
url(http://www.mysite.com/images/prevlabel.gif)
url(http://www.mysite.com/images/prevlabel.gif)

This oonly worked as long as I kept all the other images involved with lightbox as they where.

So after some more trail and error etempts, it seems like its this part thats referencing to all the images:
url(data:image/gif;base64,AAAA);

How can I point this to a url like http://www.mysite.com/images/ ?

Thanks