You might try looking in local libraries. They often have a wide range of novels, and if they don't have it in stock, they may be able to order it for you.
You could also try searching on specific book search engines. They can direct you to different platforms where the 'Do Dil Ek Jaan' complete novel is available. Social media groups or forums related to books might also have recommendations on where to find it.
I'm not sure if it's extremely popular on a global scale. But it might be popular within certain regions or among specific groups of readers. Without having read it, it's hard to say exactly what it's about, but from the title, it might be a love - themed story perhaps involving two hearts (do dil) and one life (ek jaan).
The content in episode 2 of the novel might involve further development of the main characters' relationships or new plot twists. But it really depends on the author's imagination and the overall story arc.
I have no knowledge about this particular novel. You might try looking for reader reviews on platforms like Goodreads or Amazon, as they often provide insights into the plot and characters.