how to cover the video

Would you like to cover the video or how to make the cover for my video?
do I have to insert an image already made to be my video cover?

Not sure what you mean by “cover”.
Could you be a bit more descriptive or provide video links to what you are seeking?

Maybe you mean thumbnail (possibly for youtube)
opera_2021-11-17_17-23-24

You can cover your whole video or in parts with a color clip, or an image. The color clip or image/video needs to be above V1.

Color clip generated from Shotcut

Image

i was acing same problem, but after see your reply i solve it. so thank you for sharing your reply