How can i insert text onto (opaque black box) image same as platform pro demo?

[hypman 9]

Hi guys If you look here http://www.pagelines.com/demos/platformpro/ and look at the 4th and 5th images, how do i make an opaque black box to write text onto? Is a certain type of photo editor needed or can basic ones do it too? thanks Garry

[catrina 103]

This is something that the theme does automatically (if you use the feature slider in PlatformPro and add title/text to a slide, that opaque black box will show up on the slide image).

[hypman 9]

In platform pro but not iblog pro? (i managed to sue GIMP to do a similar static image anyway. Thanks