Hi Nancy!
I can tell you from personal experience that your weight is fine for a road bike. A couple years ago I was over 347lbs. (Not anymore -- yaya me!). I have a Specialized Vita, and I even have some snooty comp wheels my husband put on and it was fine.
Admittedly though, when my husband put the wheels on I was like, "Uh, where did all the spokes go?" "No way is that ever going to hold my a$$!" It did... now at 212 (and still dropping), those same wheels are fine and have never had to be trued-up, but we did check them from time-to-time when the bike was tuned up.
Congrats on your decision to ride. It was the best thing I ever did. I am no pro, but I certainly enjoy it. Next weekend I'll be doing my first MS150.
Donna