title: custom field background image
body: <p>I have looked high and low for this, but can't seem to find an answer... I have a wordpress site that used custom fields and can upload images to it and basic copy in a tinyMCE, but I was wondering if there's a way to have it so that a user could upload a background image to wordpress, and then have it appear on the site in the area that's designated?</p>
  
  <p>I'm using Advanced Custom Fields to upload / edit fields.</p>
  
  <p>One idea I have, is to have it so that a  calls an absolute url that a user uploads stuff to... but the problem is that if a user uploads down the line, wordpress would change the url of where things are uploaded.  For example, img src="october2013/backgroundimage", 2 months down the line it would be img src="december2013/backgroundimage".</p>
  
  <p>Is there a way I can designate the url an image is uploaded to in wordpress?</p>
  
  <p>Thanks</p>