You can export Access data to PDF, Excel (xls*), or text (txt, csv) manually on the navigation pane or with VBA commands such as DoCmd.OutputTo.  To do it 837 times, you may use some kind of a looping in VBA.  Regarding transmitting to a secure server, you need to find out from the other party how exactly it's supposed to be done.  Some may require you to send via an FTP client, web interface, EDI, or some other methods.

not 837 times,   standard 837 file format is used for medical billing claims

If you are talking about EDI 837 documents, you need to be well-versed in the EDI technology and, of course, how to implement it in your system (Access, in your case).  If you can't do it, you need to pay others to do it (there are "EDI service bureaus" that do this).  I've done it, and so has Richard, so it's not impossible.  It all depends on your expertise, and, if you possess the expertise, whether you want to implement it all on your own or hire a consultant to do it.

If you are not well-versed in EDI technology:

EDI is an industry standard, but it is implemented differently by different companies.  As I said, you need to ask your trading partner (to whom you are to send the 837) for the exact requirements of how to compose such a document.  They will give you an "EDI 837 mapping specification" (or "implementation guide") that will look something like the picture below.  It basically tells you how to compose the document.  It is a highly structured format that you need to adhere to precisely (where to put each field, how long each field should be, etc.).  The red text "data sample" in the picture below is what a finished document would look like.  It is in text format, and it uses delimiters to separate each field.  A line with address info would look like:  

     N3*P.O. BOX 48130~N4*JACKSONVILLE*FL*32247

If you are well-versed in VBA, writing code for exporting Access data to a delimited text file is not the most difficult thing in the world.  The difficult thing is to keep up with the requirements of your trading partners.  They may revise the mapping guide, and you'll have to rewrite your code.  And if you have lots of trading partners and/or lots of documents you have to do this for, the amount of your work multiplies.