I've never written any Perl script without subroutines (known as functions in other programming languages).

You don't need to use goto, you define subroutine and call it like this:

# define it
sub Add {
    my ($x,$y) = @_;
    return $x + $y;
}
# call it 
print Add(5,3);
# it will print out 8
[download]

You may want to tell us what's the problem you are trying to solve so we can help you deciding what would work for you.