Syntax for tagging files, or extracting fields from tags

I am new to this forum & am just getting used to the features of MP3Tag, so apologies if this is a "dumb question". I used to use Tag&Rename, and was pretty compitent with all of its features. However, I find MP3Tag to be a far more readily accessible application. I am struggling to follow the process for either renaming tags from fields, or extracting elelments of tags to fields, so wonder if there is an "idiots guide", somewhere on this forum, which will help me to understand the syntax I should be using to accomplish these tasks. Any help or direction would be very greatly appreciated.

I would try the documentation: