I'm just starting out selling my photos and trying to figure out the best way to track which items are selling. I see that there is a Comments section in the Library module but don't see how to activate it. Or is there another place for me to document the sales for each picture. I want to be able to see the picture and know the sales so I know which ones to continue to produce. Any suggestions?
The Comments field is for services like Flickr,Facebook where other members can add comments about your images.
Not only can you upload and manage your Social Accounts postings, but you can sync those comments back to LR for reference ...
So if you don't have it set up to your Facebook,Flickr (etc)account .... service not supported comment
You could use keywords like Sold or could Color code or Flag Pictures to Filter them. See Adobe Photoshop Lightroom Help | Find photos in the catalog
Or is there another place for me to document the sales for each picture. I want to be able to see the picture and know the sales so I know which ones to continue to produce.
As Aakash said, the Comments field shows comments that have been added by users on services like Flickr.
For your purposes, you could use any of the metadata fields that you're not using for some other purpose, e.g. EXIF User Comment, IPTC Headline, IPTC Instructions.