1. Make a HTTP-POST call by using URLConnection and also getOutputStream()
in URLConnection, and send  the data  according to
http://ftp.ics.uci.edu/pub/ietf/http/rfc1945.html (may be there is a
regular api or product that simplifies this)...

2. Use regular HTTP technology (servlets etc) and only use the applet  for
formatting, when the data is to be sent, copy it into a regular form-input
field and post the form (maybe even in another frame than the main one).

There are a great number of (more or less complex) "text editors" that can
format text that uses version 2 above. The basic function of these modules
is to act as a richer textarea-tag than the one defined by HTML.

I dont have any examples of how any of these alternatives can be done but i
have seen it done several times and then always only one of these two
versions... (ehm actually i've never seen a POST done by using the java.net
api).