First of all, you must Enable (Allow) upload support and choose an upload folder in NetworkActiv Web Server before your clients can upload files to you.
To enable upload support and to choose an upload folder, please click on the button entitled Security options (located on the right side of the main dialog). On the right side of the Security options dialog there is a large square outline entitled Upload support. Within this large square outline is contained the security options pertaining to and including the ability to enable/disable upload support and the ability to choose an upload folder.
POSTing files using a form is a rather simple task. Using a simple text editor such as Notepad or Wordpad, copy and paste the following HTML text into a new text file.
After you paste this text into the text editor, save the new text file as Upload.html. For it to save the file with the correct file extension, you may need to choose the All Files option from the Save as type: dropdown list on the Save or Save as dialog.
Make sure you save the file to a location somewhere within a folder that you are currently serving. If you have done this all correctly, when you access the file via a web browser, you should have a form with an appearance similar to the following: