In Cura you can click generate support and it will determine where to place them. Give that a try and see how it turns out. You can dive deeper into the support settings as you learn more.

I learned a lot about 3D printing on YouTube. Makers Muse, The 3D Printing Nerd, Teaching Tech, Dr. Vax, CHEP and other channels are a great resource that I highly recommend. If you know a more experienced printer, their advice can be invaluable as well.

As airscapes said 3D printing is a lot of trial and error. But don't get frustrated, everyone who 3D prints has been right where you are. If you stick with it, in a short time you will be regularly producing great prints.