Shoutbox

i have a window wich is acceable from the plus menu and i have two editcontrols but i want to let them have a value wich is in an textfile and when it is changed it saves the new line to the text file so like this

you just installed the script

you open the window and the default line is loadded in the EditControl(from a textfile) so you see a text box with the default line

The user then changes the line for another line and clicks a button: save

the old line is deleted from the tectfile and replaced for the new line

then the user reopens the window

and in the textbox now is the new line

i cant seemto figure this out so
plz help mme

p.s.
If you only know a bit of this plz post it
every bit helps