Grey grid query

Hi there,

I am quite new to this editor (have only been using for a month or so) and have a query:

I have a page which has been created prior to my involvement and it has a grey grid that cannot be seen on the live website (i.e. not a table). I need to expand it further down the page to add more content but cannot find the option. Does anyone know where I can find it? I am using 2.6.6.

Many thanks
Matt Postlethwaite