var howToDivVisible = false;
function ShowHowTo() {
 var howToDiv = document.getElementById('howto');
 var openImage = document.getElementById('imgopen');
 var closedImage = document.getElementById('imgclosed');
 
 if (howToDivVisible) {
 howToDiv.style.display = "none";
 openImage.style.display = "none";
 closedImage.style.display = "inline";
 howToDivVisible = false;
 } else {
 howToDiv.style.display = "block";
 openImage.style.display = "inline";
 closedImage.style.display = "none";
 howToDivVisible = true;
 }
}