Sending attachment files, along with sending a Google Docs form, by email?

Question

I create the form using GDocs and then take the form to my web page so that I can edit the form directly (so I have full control over the form code).

Now I can send the results of sending to Google Docs , and then received the results by email to me .

I want to add file attachment to these views using:

<input type="file" name="datafile" id="filedata" size="40"> 

I know that I can use the extended arguments of mailApp.sendEmail, in particular the attachment argument, or the inlineImages argument.

But how do I access the values ​​of files to attach them?