Okay, the first thing to do is try to figure out where the noise is coming from. It might be rubbing on the front derailleur now, which can be a super-easy fix. So if you can put the bike in a stand or have a friend hold the back end up so you can peddle it slowly and look very carefully at the front derailleur, you might be able to see if the chain is ticking against it.

If that's not where the noise is, then it might be hitting the back of the next bigger chainring in front. They might have altered the chainline very slightly by putting on these different chainrings. Different chainrings can be thicker or have thickness in different places, so the chain might be more apt to tick against the larger chainrings when you are in a small cog on the back and the small chainring. It's usually best to avoid being in the smallest ring and smallest cog, but I don't think it should be making noise when you're in any of the *three* smallest cogs.

WorldWind is right too about your chain possibly being worn and lengthened, so check that with a ruler to see if the link pins line up perfectly at the 12-inch point. Your cogs might be worn too.

And, I know this is terribly frustrating right now, but look at it as an opportunity to get to know your bike better. You are taking your first steps into the world of bike mechanical work, so that in the future you won't have to feel like there's nothing you can do until the shop opens. It will become a real source of pride for you to confront a problem and fix it. There will still be frustration, of course, and that's when you'll come and post here and we'll all help you figure it out. Hang in there!