how do i make my photograph page be in a gridlock?

How do i make my photography page so that the photographs will be in gridlock like this:

my page:https://hopelesswandererfilms.squarespace.com/photography/

make it look like this:http://www.squarespace.com/templates/?q=flatiron

The simplest way would be to switch to the Flatiron Template :)

Or you can try making a Gallery and adjusting the settings: http://help.squarespace.com/guides/using-the-gallery-page