I will look into that error message. You should not be seeing that. Import listings is for CSV input of listings which is in its first Beta. I have much refined version coming out in the next few days.
There is help, although I'm usually behind in keeping that being upto date. You can access it here
http://zimpro.co/blog/ or from the program itself. Most screens have a help button dedicated to the screen being shown.
If you goto Filter Listings (right hand button on the top you will see ALL of the listings from your shop. By double clicking the column header it should bring up the appropriate screens and/or input to bulk edit that column.
There are several other functions of the program as well such as a tag gulper which will tell you how your shop compares to other shops and a report generator. We're here to help with any questions you may have. We'll also take suggestions on how we can improve.
Thanks