By writing! The first thing is probably to find a subject that interests you, because you're more likely to make an interesting hub about it. The point of hubs is to make a good go-to article (especially if you're doing it to make money.) A well-researched, clearly written and not too complicated article about something that you find interesting or exciting is the best way to start. But I would also be sure to edit. A lot of misspelled words really detract from a hub. The template for publishing your article is quite easy to follow. Good luck!