Hi
Yes, don't use black letters unless you have a contrasting background. Unfortunately the text background option seldom looks right and you would do better to simply write your text in a colour that will be well seen over black and leave the text background transparent.
Write your text to a width and font size suitable, in say, yellow. You can change colour,size and font later if it doesn't fit first time around. When completed it will be added as an image to the clip bin and also placed onto the overlay track whch you should then expand. You can now click the FX button and use POSITION to move it onto the right hand side (or the left) of the frame where when it is to be viewed. Use Sequence Preview to monitor its position. it will appear over the black background.

Nat