window.onload = function() {
  applyDefaultValue(document.getElementById('tfa_Name'), 'Name');
  applyDefaultValue(document.getElementById('tfa_EmailAddress'), 'Email Address');
  applyDefaultValue(document.getElementById('tfa_PostCode'), 'Post Code');
}

function applyDefaultValue(elem, val) {
  elem.value = val;
  elem.onfocus = function() {
    if(this.value == val) {
      this.style.color = '';
      this.value = '';
    }
  }
  elem.onblur = function() {
    if(this.value == '') {
      this.value = val;
    }
  }
}