How to do SEO?

I am learning SEO. Does anyone have good idea to make backlinks?

Welcome to the forums, @jerrymo.

If you look around the #marketing section, you will find many threads discussing this topic, including a recent one here:
How to build valuable backlinks?

I suggest you read some of those, and if you have a more specific question which remains unanswered, then post again.

I would, however, suggest there are more useful ways to spend your time. I would recommend reading and following Google’s Search Engine Optimization Starter Guide, rather than focussing on outdated techniques.