I want to earn free BTC, but I do not know how to do it. Whould someone help me to do it?
You can't earn without investing my friend, there's no such thing as a money fountain.
If you want to earn money, or cryptocurrency, learn how to trade, learn how to deal with the market and study how it moves.
Maybe, the thing that you are searching for are bounties, there you also can't have money easily, you need to become better in crypto space.