open(PAGE,"3.txt") || die "I can't open yourfile.txt";

@File =<PAGE> ;  #store the contents of the file into array
close(PAGE);
$Ctr = 0;

foreach (@File){     # loop through file
{
$_ = $_ . "\n" #add extra newline to each line
}
$Ctr = $Ctr+1; #increment through the array
} #end foreach

open(PAGE,">3.txt") || die "I can't open yourfile.txt";   #write the array contents
print PAGE @File;
close(PAGE);