Unsure about setting up a network: Making PC discoverable

Hey everyone. I'm completely dumb to setting up a network. After my father passed, I got a tablet and a cellphone. I have to take notes and photos often and would like to be able to just access these devices right on my computer. I'd also like them to easily share my internet.

I think I have most things figured out, but I'm stuck on whether or not I want to make my computer discoverable, and whether or not my network is secure from neighbors.

Making my computer discoverable -seems- to be the one step I'm reluctant on. How do I know if it's secure from others, how do I know it's password protected, etc. I'd like to be able to have full access to my things even though I live around a lot of people. Thank you very much.