I often use stills from my videos as DVD backgrounds. To do this, I first position the timeline marker so the monitor shows what I'd like to use for a still.
Then I do File–> Export –> Media and change the format to jpeg in the export settings box.
I change the name and destination as necessary by using Output Name also in the export settings box.
Click queue to open the Media Encoder
Start the encode by using the "Play" arrow in the upper right corner.
Should be done quickly. It often takes a few tries to get just the right frame.
Hope that is what you're looking for.
