function secBoard(n)
{
 for(i=0;i<secTable.cells.length;i++)
 secTable.cells[i].className="sec1";
 secTable.cells[n].className="sec2";
 for(i=0;i<mainTable.tBodies.length;i++)
 mainTable.tBodies[i].style.display="none";
 mainTable.tBodies[n].style.display="block";
}