From the New/Edit form, you can provide the following information about your Reference Unit:

Title
The title is a required field.  This should be short, but should also clearly indicate the topic covered in the unit. For example, a unit about the New England states could be titled "The New England States" or even more simply, "New England." Avoid lengthy titles like "Maine, New Hampshire, Vermont, Connecticut, Massachusetts and Rhode Island."  Keep in mind that you will also be able to provide titles for the individual pages in your unit; this would be a more appropriate place to provide "Maine," etc. as titles.

Description
This should be a short (one or two sentences or phrases) description of the unit.  For example, "An exploration of interesting facts about the six New England states."

Keywords
Keywords are optional, but they may help visitors find your content through search on the site. This is a list of words or phrases related to the content of your unit, separated by commas.  For example, "new england, maine, new hampshire, geography, history, united states," etc.

If you share your unit with the public, the site administrator will probably tweak your keywords, so don't stress too much over this field.