APPEND x TO FILE y statement appends the value of
x to the file called
y. If the file already exists,
x will be added at the end of its contents.
APPEND <NUMBER or NUMBER-VAR or TEXT or TEXT-VAR> TO FILE <TEXT or TEXT-VAR>
APPEND "\nHow are you?" TO FILE "hello.txt"
in this case, the file
hello.txt, created here and modified as stated on that page, will contain the text
Hello there!How are you?