i cant for the life of me figure out how to change the date from default mm/dd/yyyy to the european dd/mm/yyyy

the manual states to use:

$.datepicker.formatDate('yy-mm-dd', new Date(2007, 1 - 1, 26));

so far i have:

$('#next_date').datepicker();

which shows the calendar fine but im not sure where the first line of code goes. this for example disables the calendar, nothing shows up, no js errors reported

$('#next_date').datepicker.formatDate('yy-mm-dd', new Date(2007, 1 - 1, 26));