the get method attaches arguments to the end of the url being called so your submited page would call something like http://www.yourdomain.com?paramone=123¶mtwo=999 etc..etc..
but your sumbit form will handle this for you. just set the method to GET ...or POST ..dosn't realy matter for what your doing. now you should find that your php page that you submitted to now has access to the variables passed to it....in this case $paramone and $paramtwo with values of 123 and 999. now with these variables set up you can assembly the html that php will output and call your applet.e.g.
echo"<param name=whatever value=$paramone>";
i think that answers it..if you want to pass arguments from the applet to a php page then its a different ballgame alltogether. java dosn't support get or post..you have to open socket connections directly and pass raw header data..if your applet wasn't programmed to do this then forget it without a crash course in java
hope this helps