help question about transparancy background


I need to build this site: in upfront.

The homepage needs an other background (the peacock), and the green boxes should be white transparance. So how do I get a white textbox with background color opacity of 70 %. And I want also a button in it and the second e-book part with an image and button.

Can you please say how I do that. I’m building the new site in upfront on this domain: