How to add a blank space between featured slider and menu?

I am sorry to bother you again, but I would like to leave a space between the menu and the slider( http://i.imgur.com/aShWjAV.png ), could you please let me know how I can do it? Thanks in advance for your reply!

Go to Theme Options – Other – Custom CSS and add the following and save it.

#main-nav {
	margin-bottom: 20px;
}

Of course you can adjust the size of the margin.