function insertTag(id, begingURLtag, endURLtag) {
  myField = document.getElementById(id);
  if (document.selection) {
    myField.focus();
    sel = document.selection.createRange();
    sel.text = begingURLtag + sel.text + endURLtag;
  } else if (myField.selectionStart || myField.selectionStart == '0') {
    var startPos = myField.selectionStart;
    var endPos = myField.selectionEnd;
    myField.value = myField.value.substring(0, startPos)
    + begingURLtag + myField.value.substr(startPos, endPos - startPos) + endURLtag
    + myField.value.substring(endPos, myField.value.length);
  } else {
    myField.value += myValue;
  }
}