simple (?) help needed

ok, so this is the thing

i've got a .swf that loads a variable (" text ") from a text file into a dynamic text area

« loadVariablesNum("textfile.txt",0); »

so, in the .txt file i've got

text= bla bla bla

what i need, is a php script to edit that .txt ... does anyone know one? i was looking for something with a login area to enter the php backoffice, and easy to use.

anyone can help?
thanks in advanced :)