Welcome to the forum!
There's a few different things to look at when getting new rims/tires. Sorry if any of this is trivial, you mentioned you're not really a car person so I figured I'd tell you everything.
The OEM (Originally Equipped from Manufacturer) sizes are:
Tires:
17s: 225/55R17
19s: 225/45R19
Rims:
17x7.5 , Offset +50
19x7.5, Offset +45
The 225/55/R17 translates to 225mm wide, the sidewall's height (aspect ratio) is 55% of the width, and a 17 inch inner diameter for fitting on the rim.
The 17x7.5 +50 translates to 17 in diameter rim, 7.5 inch wide rim, and +50 means the rim mounting is 50mm closer to the outside of the car than the center of the rim (basically, how far back/forward will the rim sit in the wheel well, where +50 means it sits inside more).
Using the manufacturer numbers
and this awesome website, you can determine where the differences will be (and how much) if you're swapping rims/tires.
TL;DR - If you get a bigger rim, you'll want to get a smaller tire to compensate for that so they don't mess with your speedometer or rub or anything. There's a bit of wiggle room on most cars to increase the size without any issues. For example: I run on 20x8.5 E+35 rims with 255/35/R20 tires and they fit perfectly with zero negative effects, besides feeling the road a little more since the sidewall is thinner. So long as you get rims/tires within the range of the OEM, you'll be perfectly fine.
