What sort of scripts do you have installed ? PHP ? Perl ?
All you need on the page is a simple form with an <input type="file" name="file" />. Also in the form tag you need the 'enctype="multipart/form-data" ' attribute.
When the form is submitted, the file is automatically uploaded and stored somewhere on the server. The script then copies the file to the desired location (need to ensure permisssions will let you write to the directory).