Extending Image Module with new fields

Hey all,
We recently purchased Sitefinity 5.2 and need to extend the existing Image with a short description field.  All of the posts I have found are regarding 3.2 and are not helpful.
How do I extend an existing Module (Images, News, etc...)?
Thanks much
Mark

~/Sitefinity/Content/Images there's a link at the bottom right for custom fields...add whatever you want in there and it'll just show up as a new field when you edit an image :)

**EDIT** there already is a description field on an image though, or do you mean like a summary\shorter version of that?...regardless the instructions above should let you extend easily.