Hi Jacquie,
Glad to be of help! In answer to your question, generally you can't check in online and must do it at the airport - more and more airlines are using the electronic booths for us to check ourselves in these days and after printing boarding passes, we then go to bag drop. If there is no booth, just go to the check in counter (if there appears to be none, go to a bag drop counter and ask if you can check in - I've done this numerous times when there hasn't been a specific check in desk). There is usually a member of airline staff loitering around to give assistance if you get stuck with this. The thing I really don't like is that some airlines now get you to print off your luggage label and affix it yourself to your luggage - it's a bit complicated to do until you get used to it (I haven't yet!) but again there is usually a member of staff to help with this. Don't worry about it, you'll be fine!
The main exception to checking in online is with EasyJet and Ryanair when I think you have to do this yourself before you leave home, but JY should indicate this clearly in your final documents. I think if you are one of the fortunate few who upgrade your flight you can check in online and choose your seat etc. but those of us going cattle class can't do this on most tours, as the booking reference is for the group.
All the best,
Bob