I do it by simply using a blank slide from Power Point.
Open Power Point and set the background colour of the slide to black. Then do a "save as" and you have the option to save the slide as a jpeg. You don't even need to save the Presentation itself if you're not going to need any other colours of slides.

Then just drag and drop that jpeg into the timeline of Movie Edit and duplicate it so you have one at the start for your titles and one at the end for your credits.
You can increase its size in the video monitor if necessary and also stretch its length in the timeline for however much time is necessary for your titles and credits.

You can use other programs to do the same thing but I find Power Point the quickest route. I use Power Point quite often for that application among other things like creating masks for use with the chroma key functions.