Set the text to display
Decide what you want your usebar to say. Type that into the box, and the preview will update when you click outside of the box.

Set the size of the text
Choose how big you want the text to be. 12 is the average, but you can experiment and see what suits you best.

Set the position of the text from the left side
Depending on how long the text is you entered and the size of the font, you may adjust the number of pixels the text is from the left side. You usually have to play around with this number until you get it quite right.

Set the opacity of the stripes
Do you see those black stripes on the preview image? You can make those blend into the rest of the picture with a setting like 25% or 50%, or you can have them stand out as a black color, with an opacity of 75% to 100%. If stripes doesn't fit your style, then say 0% to remove them.

Double the number of stripes
This does exactly was it seems like: doubles the number of stripes in the preview image. It doesn't hurt anything if you don't like this setting, so try it out.

Set the opacity of the white overlay
The White Overlay is that light white thing at the top of the image that gives it a lighting effect. Try out different opacities for this and see what you like.