submitting a pdf directly to the server

You are simply uploading a file.  To do this you need to use either html5 and a serverside scripting language to handle the file.  Or you can use php/asp/3rd party components.   You can also use web services where the files are stored on a 3rd party server

Are you familiar with php or asp or another serverside language?

I can do it in any language.
If I embed the pdf on my page, how does that save in the pdf know where to save it.

There are many ways to go about this.  Here are a  couple.  You are starting with a multipart/form-data form.  Then using your scripting to handle the upload.

php  http://www.w3schools.com/php/php_file_upload.asp

HTML 5  http://www.html5rocks.com/en/features/file_access

php

I don't think you understand the question.
I want the pdf to be embedded on my page. Not a link that opens on a different browser.
I don't want the user to have to save the pdf on their hard drive and then find it and click upload.
I've seen some sites, like insurance requests, that you type on the pdf on their page, and when you save, somehow it saves and closes and the company gets the data.
How did they set it up to upload without the user seeing anything?

There are some expensive PDF document servers out there if you want to use them.

But this shouldn't be anything different from displaying data from a database source into HTML form, have a user edit the data and save back the changes. You just need to find/create a class that you can use to generate a PDF document instead of HTML form and parse the user input to update the database when saving it.
I do not know of any specific class but I am sure there are some available if you google for it.

CyanBlue

I have adobe acrobat pro.
is there somewhere i can get documentation to figure out how to program the file so it'll send data out as xml?

There should be a menu item for forms.   I have File, Edit, view, Document, Comments, Forms, Tools, Advanced, Window and help.  Open up your document, save it as something, then go to forms > Create New Form and follow the wizard.  If you have a ms word doc for instance that you create a pdf from where you have questions.  Sometimes the form wizard can detect where to place fields.

http://help.adobe.com/en_US/acrobat/pro/using/WS58a04a822e3e50102bd615109794195ff-7e0d.w.html

Working with pdf forms is not the easiest thing at first but once you start doing it works out.  I found it faster to create what I want in another program, make the pdf then run the forms wizard.