How do I add text on top of existing video (transparent background)

I am at my newbie wits end. I have been using both the media generator and the text generator to try and add text to sections of my video. For example, in the Media Generator, I select text, select the first checkerboard style sample text (Arial on a transparent background) drag it into the timeline on top of my video. When I play the area, the text appears, but it is on a black background obliterating my video despite my choice of the transparent background. There are two triangles at the top right and top left of the text frame. If I move either one of these to the far right or left I get a fade transition that shows my text fading in and out over the video. I don't want this either, I just want the background to be transparent and my text to appear on top of the video which continues in the background. I have spent hours reading documentation and trying to figure out how to get make the transparent background transparent, and I wondered if anyone can help me do so.

I have Vegas Pro, downloaded today for the 30 day free trial. If I can't get this simple thing to work, I can't use this software for my projects.

Thanks for any help,
Mark