delate white square under the menu; widgets; posts organization

Hello,

I really like this theme, but there are few things that i cannot change and I need your help.

First of all, under the primary manu there is a white “square” where is written the name of the page or of the article that I have selected in that moment. How can I change the white color in order to the have the whole page black?

Secondly, how can I add the arrow that connect different sections of a page? For instance in your preview where is written “a little about me”.

Third, how can I delate the space for the widgets on the right of a page?
and is it possible to organize the posts in horizontal instead of in vertical?

Thank you,
Sara