myLine = 3;
myMes = new Array (
 '<IMG src="../00index/img10.jpg" width="430" heigth="70">',
 '<IMG src="../00index/img11.jpg" width="430" heigth="70">',
 '<IMG src="../00index/img12.jpg" width="430" heigth="70">'
) ;
myRnd = Math.floor (Math.random () *myLine) ;
document.write (myMes[myRnd]) ;