New and need a little guidance

[CorsairMac]

welcome to the boards Diana!......congrats on the bike!! It'll come easier the more you ride and with time! like Denise said:

in front - the bigger the ring, the harder it is to pedal.
in back - the bigger the ring the easier.

You've got 3 rings up front and 7 in back sounds like yes?.....so you've essentially got at least 3 - maybe 4 rings in the back for each ring up front!.....play around with them - you'll find your most comfortable combo and then work out from there. Just make sure your chain never looks like this \ or this /. That's called cross-gearing and it's really hard on your chain!
Also, it's easier on you and your knees to pedal in a lower gear (higher cadence) then to try and mash your way thru a higher gear.

Have fun and keep us posted!!!