In the user guide, the directions for setting up packages show this:

" On the action bar, click Content and Benefits. The Content and Benefits screen appears "  Great...but in the image, it shows:

 "Merchandise Memberships Series Price Levels etc"

across the top -- I don't have that on mine, and I can't progress any farther without it. What step have I missed?

The fields should show by default unless they have been hidden.  With the Contents and Benefits window open, click on the design icon (should be 5th icon from the left).  Make sure the Display column has "Yes" selected for all options.  If it's still missing, I would contact support. It could be an issue with user group permissions or your profile (if you're not logged in as System Admin).

 Thanks, Rosita. I was hoping it was something totally obvious, you know, like something I'd forgotten to do. I pretty much just followed the User Guide instructions to a "T", so I was baffled.

 I'll shoot a request over to support. Thanks!

We've found an issue with this happening in 3.340.  It should be fixed permanently in our 3.400 release, but until then you can contact Support and they have a script to run on the db server to fix it temporarily.  Just make sure your profiles are how you want them, because editing and saving a profile causes the buttons to drop off again.