Set the appropriate video size.
Clip clips, divide videos, arrange them, step on them, and so on.
Add audio, including background music and sound effects.
Add subtitles and subtitle effects.
Apply some picture styles, such as filters, colors, moving scenes, beautifying, etc.
Finally, just learn how to adjust the export settings, and then export the video.
Of course, all of the above are relatively broad, so you can watch more and practice more. Start from the general direction above, step by step.