So much of this depends on what kind of riding you're doing. If you're just riding easy on a nice flat bike path, you're probably fine the way you are. If that's the case, just ride for awhile until you become more familiar with your needs and more familiar with your bike.

If you're riding hills, especially if you're having trouble making it to the top, changing your gearing to something much easier is worth considering. Your easiest gear combination is the small (or smallest) chainring with the largest rear cog. If you count the teeth on both and use the formula front teeth over rear teeth, that tells you your "gear ratio". So, for example, if the small chainring has 40 teeth and the largest rear cog has 28 teeth, your gear ratio would be 40/28 or around 1.4.

You'll have a much, much easier time climbing hills if you create a gear ratio close to around 1.0. So, for example, you might consider changing your 40-tooth chainring to, say a 34 and changing your largest rear cog to around a 34 as well. If you can only get a 32 or even a 30 on the rear, that would still be much better than what you have now. Note that there is more to understand about gearing and that other changes will likely be required but this should get you started.