You'll find further information about how to edit videos under following link:
Follow the link below to get more information abozt editing videos in portrait format:
Editing videos in portrait format
Click on following link for further information about editing picture in picture (PiP):
I have a video. I want to cut out the parts that I don’t need, what should I do?
In Express mode:
1. Open Nero Video, drag video into storyboard
2. Move the cursor to the frame you want to cut. Move the mouse to the split button. Click Split button. Video is cut into two parts.
3. If you want to continue cutting, you can cut into several parts.
4. Select the unnecessary parts, delete them.
5. You can add text/transition between videos.
6.Export to the format you want.
In Advanced mode:
1. Open Nero Video, drag video into timeline
2. Move the cursor to the frame you want to cut. Select tool "cutter" on the right side of timeline, move to the position of cursor and click. Video cut into two parts
3.The remaining steps are the same as Express mode