Welcome to the forum!!!
Test kits are a GREAT investment! One of the best and most commonly used by members here is the API Liquid Master test kit (Here's a link to it on Amazon:
As you can see, it is $20, but it will last YEARS, and is, in my opinion, invaluable. It allows you to test your water whenever you need to, at any time of the day, without having to get in your car and drive somewhere. This is especially important when you're cycling a tank, as you'll need to test the water daily, sometimes even several times daily! It's alos relatively easy to use, I can test my water for ammonia, nitrite, and nitrate in less than 5 minutes. Much quicker than driving to a store!
The next step would be to find out the Ph, Kh, and Gh of your source water. If you're on city water, you can usually find this on your water suppliers website. If you're on tap or can't find it, API does sell a test kit for gh and kh.. (Here's a link!
). The Master Test Kit already has a ph test in it, yay! :D
The numbers from that will determine just how 'soft' or 'hard' your water is, which plays a role in fish selecting (once your tank is cycled, of course!)
Now, you mentioned you bought live plants? AWESOME! I LOVE plants, probably almost (if not more, truthfully) as much as I love fish. What kind of light do you have on your tank? What kind of plants? (Some plants need fertilizers and root tabs, but don't worry! They're cheap, and we can guide you in the right direction of good brands to choose from)
What kind of substrate do you have? Sand, gravel?
As for cycling, I'll leave that for another member to explain, I'm not the best at explaining it unfortunately!
My first experiences in fish keeping weren't the best and I made a LOT of mistakes (most of us here have, don't worry! It's how a lot of us found this forum, and grew to be passionate, responsible hobbyists from it!).
I will let you know now though, in terms of fish-keeping, a 10 gallon is quite small. It's even considered to be a nano tank! This is because fish can get either large, active, or need large schools, or all of the those combined, and need a larger tank to thrive. With a ten gallon, you're going to be looking at very small fish that stay small (pet stores usually sell very young fish which is incredibly misleading as to what size of a tank they're gonna need.) Many people just keep either a betta fish or a shrimp colony (or the two combined) in a ten gallon. Now, that said, it IS possible to have other fish in a ten gallon, but they usually aren't the type of fish most readily available (though this does depends on your local pet shop!)
Phew, sorry for such a long post!! Can't wait to hear back from you :D And again, welcome to the forum!