remember that you are doing this for fun and a cause, not a race. Feel easy about starting at the tail of the tail end and find your pace. There will be other slow riders and you will find that since you aren't hammering down the road, you will have time to chat briefly with people as you ride past or with them. Do ask if you can ride along for a while if you find a group at your pace. Be honest about being a beginner and not too sure of things. You will find that most charity riders are just out there to have fun and lolly gag along. Stop at the Sag stops but keep your stops short. Remeber to warn other riders, thank the sag people or the police officers doing traffic duty. With the exception of the police, they are all volunteers and while the police do get paid they still deserve to be thanked on general principles. If someone makes you uncomfortable, slow down until they pull away. Start slow, find your pace, chat up strangers and enjoy your ride.
It will be fine.
marni
Katy, Texas
Trek Madone 6.5- "Red"
Trek Pilot 5.2- " Bebe"
"easily outrun by a chihuahua."