Sydney theme : Slider Problem

Hello dear WP users,

I’m having trouble with my website’s slider. I use Sydney theme, and I’d like to remove the blank part above the slider.

here’s my website : http://troubleobsessionnelcompulsif.fr/

I saw some posts where you need to add some lines of codes. Problem is that I’m a total beginner and I have no idea how to do this…

Thanks by advance!