The supervisor needs to roll the books forward to that period in the right year or unlock it. You didn't say why you couldn't select it.

I have supervisor rights, but don't know how to "roll it forward" without closing the periods. I am very new at the software and have never done it before.

Hi vargo05 - You will need to log in as Supervisor with exclusive access. Then go to 1-6, click Change Period, and advance to Period 1 of 2016. This will open up periods 2-12

Does this essentially mean that you can't open any periods other than January, if your prior year is still open?

No, once you open January and the rest of the months come, you can change back to a prior period if you need to (you will have all 12 periods available for the current year and prior year, if you haven't archived). Keep in mind this is just the default posting period for new transactions. You can change the posting period for a transaction just by click the numbered calendar icon in the upper right corner.