how to get the value in textbox?

hi how can i get the value of my input textbox? heres my code.
<script type = "text/javascript">
var counter = 0;
function AddFileUpload() {
var div = document.createElement('DIV');
div.innerHTML = 'Description' + '&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;' +
'File' + '<br />' +
'<input id="definiton' + counter + '" name = "definiton' + counter +
'" type="text" />' + '&nbsp; &nbsp;' +
'<input id="file' + counter + '" name = "file' + counter +
'" type="file" />' +
'<input id="Button' + counter + '" type="button" ' +
'value="Remove" onclick = "RemoveFileUpload(this)" />';
document ...