How does this goto statement work??

[Dos-Man 64]

Hello, I'm using some version of Turbo Pascal. I'm creating an MS-DOS
application. It is using the windemo.pas source code as a base. I've
altered it a bit to get it to do what I need it to do. I'm trying to
set up a goto statement, but I can't get it working. The pseudocode I
need is as follows

50:
findfirst(all directories)

repeat
do
findnext(all directories)
writeln(directory.name)

if keypress = enter then chdir(s);
if keypress = escape then end
loop

if error occurred then
end
else
goto 50

until done = false { repopulate the listbox with new
directory listing }

Can anyone tell me what is the best Turbo Pascal reference book? I
have only one book, but it's mostly pascal basics and theory. Doesn't
really delve into specifics about the compiler.