thx. I found on google something exactly what I am looking for.
<code>
<form name="form1" method="post" action="">
<input name="title" type="text" id="title" size="20" onkeyup = "checkFilled()">
<textarea name="description" cols="18" rows="5" id="description" onkeyup = "checkFilled()"></textarea>
<input name="theName" type="text" id="theName" size="20" onkeyup = "checkFilled()">
<input name="submit" type="submit" id="submitForm" value="Add Event" disabled="disabled">
</form>
<script type = "text/javascript">
function checkFilled() {
var filled = 0
var x = document.form1.title.value;
x = x.replace(/\s+/,""); // strip leading spaces
if (x.length > 0) {filled ++}
var y = document.form1.description.value;
y = y.replace(/\s+/,""); // strip leading spaces
if (y.length > 0) {filled ++}
var z = document.form1.theName.value;
z = z.replace(/\s+/,""); // strip leading spaces
if (z.length > 0) {filled ++}
if (filled == 3) {
document.getElementById("submitForm").disabled = false;
}
else
{
document.getElementById("submitForm").disabled = true
} // in case a field is filled then erased
}
</script>
</code>