Tips for first time Century Ride

I am new to the forums, and pretty new to cycling. I have done spin classes for years and have ridden for 'fun' on my mountain bike. I have this friend that is a hard core cyclist, and wants me to ride as well. I don't have a road bike (yet) so will be riding a tandem for this Century Ride.

I have been searching the web for tips on doing Century Rides, and came across this forum. Sooooo, if anyone has tips for me they would be greatly appreciated!

My longest ride so far has been around 70 miles, and have been training for several weeks. I am still not convinced I can do this well. We will ride 100 miles on Saturday and on Sunday. The first day is the toughest day, and the second 'easy' or so I have been told. :rolleyes:

It is this coming weekend, and I am starting to get a bit nervous, so please let me know any tips to help me survive!

This is the ride I will be doing.