Transparent background between text and background image???

The single page/post layout on my site is No Sidebar (full width). I use a plug in to add individual background images to the single pages/posts. The text is white and sometimes doesn't want to show up. Where in CSS should I add/change the code so I get this? I have tried everything. As before, I will NOT post a link to where the site can be viewed as the band has yet to see it. In other words: I’m developing this to show the band for their approval. Before they approve it, nobody but me will see the site. If they don’t approve it will be trashed. It's that simple. You will have to answer my questions without seeing the site. Cheers and thanks in advance