By mentioning "to get published", did you mean how to "publish your hubs" or to get established/popularity?.
I think you refer to the later. Because, now that you have "published" four hubs and the first doubt is out of question.
So, assuming that you want to get really "published"[.. :) ], i'll try to give some tips.
First and foremost, you'll have to create good informative hubs which will automatically lead your hubs to get enlisted in search engine... its not easy though. For this to be done, you have to be aware of the basic SEO techniques like concentrating on one main theme/keyword, giving appropriate tags for your hubs etc,
One of the other ways to get established is to go and participate in forums outside hubpages and leave your link along with good, appropriate comments.
A good author/hub score will help you to get enlisted in the "featured hubs" inside hub pages.
I think these help you to get started...