Video editing software from a DVD home movie -URGENT! for wedding on saturday!

Those don't appear to be compatible file formats:

About incompatible media in iMovie for macOS - Apple Support

You may also want to look here:

iMovie User Guide for Mac - Apple Support

You need to convert the DVD to a format that iMovie can handle. (The process is called ripping a DVD.) Many users in the iMovie & Final Cut communities suggest using Handbrake to convert DVD video to MP4, which iMovie can edit. Be aware, however, that Handbrake has a lot of options that must be set and it can take some significant learning to do so.

iMovie cannot import from a DVD. What you need to do is copy (copy, not move) the VOB files to your desktop. The VOB file contains the movie, including audio. You can ignore the BUP and IFO files.

Then convert the VOB fies to Mp4/ACC that you can do with the free download, Handbrake. Once converted, you can import the converted files into iMovie by dragging them into an iMovie project timeline.

You can get Handbrake here:

https://handbrake.fr/

A simple way to do it is to open Handbrake and do a File/Open Source. Navigate to your video and choose it as the source from the resulting screen. Then do File/Start Encoding. Wait a couple of minutes for the conversion to complete. Then save and import the converted clip into iMovie.

-- Rich