How to write or update information from falsh thru PHP to .txt file

1

Suppose the information in .txt like

//friend’s name
&friends= Ann,Philip,Libby&br=

//friend’s birthiday
&friend0=10/10&br=
&friend1=08/04&br=
&friend3=14/03&br=

And how to create a PHP script to edit those when input in flash?