/* Create a few variables so you won't get errors */
readings = new Array();
for(var i=0; i<=12; i++)readings[i] = new Array();


/* add the readings here, there are two ways of adding them. */
/* like this, for every day a separate line */
readings[1][26] = 'Test';

/* or like this for a whole month */
readings[1] = new Array(
    'day 1',
    'day 2',
    'day 3'
);


/* Change the contents of the div */
reading = document.getElementById('reading');
if(reading){
    d = new Date();
    month = d.getMonth() + 1;
    day = d.getDate();
    if(readings && readings[month] && readings[month][day])
        reading.innerHTML = readings[month][day];
    else
        reading.innerHTML = 'No reading available today.';
}