There are many way to earn money online . I will share here some of them.
1> crypto trading :-  First thing to understand crypto is subject to market risk. You can earn here lots of money buy holding some good coin and trading based on technical analysis or fundamental analysis. But high reward means high risk. You can learn how to trading on youtube. And start crypto trading.

2> blogging:- we all know steemit, scorum , and many site are giving rewards for post. And some site running since 2 or 3 year and they are working continuously.
So create account any of that site and start content writing.

3> Youtube:- you can make video and share on youtube if you start something unique then there is chance to grow fast on youtube.you can earn huge money from youtube.

4> playing games :- you can earn money by just playing game like rummy circle is site in india where you can play 13 card rummy with other online players and earn money just wining games. Also there is many site are provide games for money. 

5> affiliate marketing : this is best option for online earning. You can open affiliate account on amazon and flipkart site where you will get some % on every product if any user by product through your link. And if you have site you can add some product on your site and if any person order any product through your site you will get some % its depends on product some to you get up to 20%