How do I ...

Using mp3tag v2.49, I have an album where the twenty tracks are encoded with the Title tag as "Artist - Title" and the Artist tag as "Various". Using the Title tag as a source, how do I change Title to show only "Title" and the Artist tag to show "Artist"?

Example, Track 1:
Title: Love Unlimited Orchestra - Love's Theme
Artist: Various

After conversion:
Title: Love's Theme
Artist: Love Unlimited Orchestra

Create your a user-defined action or use a "action (quick)" of the type "Split tag-fields"
as source use TITLE
as mask enter:
%artist% - %title%

I don't know how to carry out your suggestion. Could you provide step-by-step instructions? How do I create the user-defined action, and how do I apply it?

Reading is clearly an advantage - e.g. in the (really) frequently asked questions.
So start here:

Too much effort and too late a response to accomplish my simple task. I made the changes manually -- much easier than wading through documentation which aren't explicit enough. The author of this program should consider creating wizards that step a user through most if not all capabilities. That said, mp3tag is a useful program for those functions I am able to utilize.

Too little effort on your part and not enough patience to deserve any help.
You should consider educating yourself instead of expecting to be spoon-fed.
That said, you can make any changes manually.