How to use retargeting in Facebook?

Please help me understand the direct instruction how to retarget audience through Fb Ads

Use your pixel and create audiences. Track the visitors from the last few days. Then target those visitors specifically.

Create a FB business page and add pixel to your website.

Then create custom audiences and set up your remarketing campaigns. And last, create remarketing ads.

You should listen to Jon Loomer. Read his blog and subscribe to newsletter - it is full with great content.

In general you should add pixel to your website and structure your content. For example if this is ecom website you can create audience of users who visited particula products or categories but didnt order; people who visited check out page but didt pay, most frequent buyers, people who bought from you long time ago but never come back etc etc etc...

You don't because Facebook do it for you and way better than any human.