Two or more integrated wordpress

I am running http://www.designexpanse.com. Its a web design showcase/gallery accepting designs from across the globe.

What I need is that I want to have articles section, interviews section and jobs section within this website but as you can see that with this wordpress I cant do that start articles. I need all the things show on every section like any visitor can move to the design section and its category from articles section. I searched for this and see alot of post but anyone of them are not exactly resolving my problem.

Please wordpress experts guide me the best solution. I hope here I can have solution for this.

Thanks in advance