{Nextgen Plugin}How to increase distance b/w gallery frame and back/next button?

Hello, i want to increase the distance b/w image gallery frame and back/next button in nextgen gallery plugin so i can place adsense ad between those.
Please look at this post of my site https://www.readstorys.com/2015/11/12-pictures-will-prove-that-you-have-a-dirty-mind/

In this i want to place adsense ad above back/next button and below back/next button.
How will i do this. Please help me regarding this.

Thanks!!