One approach...
Track one: Your main video
Track two:
ADD BLANK from the toolbar. Any color. Open effects for that track by clicking the FX on that track in the timeline.
Click the MASK icon (smaller green + sign to the right of the larger green +) and create a polygon mask. Shape it by dragging the handles in the preview window.
Click the larger green + sign and add a transparency effect. Drag the opacity slider to the far left.
Track three:
ADD TEXT of the desired color and move it to the top. Text can be place by using either the positioning icons in the text window or by dragging it in preview. Drop the clip onto track three.
Track four:
ADD text again and position it at the bottom. Drop this clip onto track four.
Track three text could be both the top and bottom, with the proper spacing, but it might be easier to do them separately.
