GIANNA345
Thank you for reading my blog. I am so glad you are getting started with biking, and you should feel great about doing 3 miles. Everybody has to start somewhere! Anyway, I don't do the 90 miles in one day. It's spread out over 9 rides in 5 days. It's 10 miles to work each day, and 10 miles back.
If you are not strong enough for hills yet, perhaps there are some flatter trails you can try that would help you build up miles more gradually?