var mess1 = new Array('<img src="imgs/foto1_01.jpg" border="0" />',
'<img src="imgs/foto1_02.jpg" border="0" />',
'<img src="imgs/foto1_03.jpg" border="0" />',
'<img src="imgs/foto1_04.jpg" border="0" />',
'<img src="imgs/foto1_05.jpg" border="0" />');

var max = mess1.length;
var num1 = Math.floor((Math.random() * max));
document.writeln(mess1[num1]);