Hi Denise and Over50Newbie!
Hope you both had a great weekend of riding! It's great to have newbies asking questions -- that's what this board is all about.
Denise, glad the gear chart made sense -- gotta love those lightbulb moments!
Over50Newbie, I don't think you can use Denise's gear chart. Your gear ratio depends on tire size and how many teeth are on each gear, and your gears may be different sizes than Denise's.
Let's see, according to the Trek website, your 2003 Navigator 300 has a 48/38/28 in the front and an 8 speed rear cassette: 11-32. Since you said that you have a 7 speed in the back, I'm not sure how to figure out which 7 speed you have, short of counting the teeth on each gear in the back.
-- Melissa