It's a convoluted process, and someone may chime in here to suggest another route. Experimentation will be necessary. But, here's the general idea...
1. Go to http://images.google.com or other image site and search for "png underline." Pick a suitable PNG candidate, right click on it and SAVE AS.
2. In Videopad video track one will be the background. In this case it's your text.
3. ADD the PNG file to the media bin, then drag it onto video track two, immediately above track one, It should display as an overlay in the preview window.
4. To size and position it, click on FX at the bottom-left of the PNG clip on the timeline. That opens the effects box. Click the green + sign at the top-left.
5. Click the VIEW icon below the preview window and verify that CLIP AND BACKGROUND is checked.
6. In the effects box, click on the SCALE effect and UNcheck the "maintain aspect ratio" box. Move the sliders to size the line.
7. Click on the green + again and click the POSITION effect. In the preview window there will be a crosshatch. Click it and drag the line. Or use the sliders.
