Investing is easy, if you have money you just have to buy bitcoin, and nowadays there are plenty of online sites where you can do it, although it is better on decentralised exchanges for privacy.
You seem to know very little about the subject, so you'd better find out a lot about bitcoin and the best way to store it before you decide to do it.
As for working and getting paid in bitcoins, Doan9269 has already answered you before to which I would add selling goods.