Full width in portfolio

Hi, my name is Costantino. I am realizing a portfolio site using the theme "Fotografie" in the free version, the address is www.costantinolorusso.it. I have created 6 portfolios and in each of them I have to add my photos, but I do not understand how to use the full width of the page. See, for example, the page http://costantinolorusso.it/?portfolio=viaggi. I posted a screenshot on the page http://costantinolorusso.it/?page_id=2. Best regards Costantino