Keilz
I've never done it before, but you'll have to make sure that the 'Farming Mode' toggle in your settings is on, and then you'll need to look for gold pouches which are scattered through the (free?) novels. Then I think you'll need to read those novels, at which point you'll have to watch ads. Watch the ads, and if everything's well, you get the free coins.
Maybe it's better to ask someone else who has actually done it to enlighten you.