Using strictures is good.

Declaring all your variables in one block up front is very bad. Not checking file open is bad. Not using the three parameter version of open is bad. Not using lexical file handles is bad.

Avoid using explicit counters where you don't need to.

Declare variables in the smallest possible scope. Be aware of the last parameter to split and use it where appropriate. Taking all the above into account the following should serve you better:

#!/usr/bin/perl
use strict;
use warnings;

my $outdir = 'D:/share/out';
my $inpath = "D:/share/in/content.txt";

open my $inFile, '<', $inpath or die "Failed to open $inpath: $!";

while (<$inFile>) {
    chomp;
    my ($title, $content) = split "\t", $_, 2;
    my $outpath = "$outdir/$title$.";
    
    open my $outFile, '>', $outpath or die "Can't create $outpath: $!"
+;
    print $outFile $content;
    close $outFile;
}

close $inFile;
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Note in particular the use of the input line number special variable $. (in "$outdir/$title$.") instead of using an explicit counter.

Update: Fix silly open error - thanks jwkrahn

open my $inFile, '>', $inpath or die "Failed to open $inpath: $!";
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Your $inpath is being opened for output.

open my $inFile, '<', $inpath or die "Failed to open $inpath: $!";
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Thank you so much for your great help. So while the output of the split remains in the default variable ,$_, what does 2 do? Also, how can I manipulate $. variable in a way that sequential numbers being added to the $title and not to the file extension: I am getting file.txt1 instead of file1.txt I tried ".txt" after ".$" but obviously didn't work Thanks again for your explanations and help

I strongly recommend that you follow the links (did I make them too subtle?) and read the documentation. In fact spending a few hours browsing the documentation that came with Perl and a few more hours reading some of the Perl tutorial and reference books ("Learning Perl" and "Programming Perl" at least) will save you days of beating your head against the desk if you intend to use Perl regularly. There are some good recommendations in the So what is your Perl book "Trilogy" anyway? thread. Visiting the Tutorials section is well worth doing too.

I followed the pattern you gave (">$filename"."$title"."$count") for forming the file name. The sequence number following the file name is what you would have got in your original code. If you want to put it before the last '.' then you need to edit the file name string. Something like the following in place of the original $outpath assignment ought do the trick:

    my $outpath = "$outdir/$title";

    $outpath =~ s/(\.[^.]*|)$/$.$1/;
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You will definitely want to read some of the documentation for regular expressions: perlrequick and perlretut at least (there is more).

True laziness is hard work

The third argument to split (in this case 2) is the limit, read the following: http://perldoc.perl.org/functions/split.html

open (OUT, ">$filename"."$title"."$count") or die "can't open";
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while (<FILE>)
{
    chomp;
    ($title, $content) = split("\t");
    open (OUT, ">","$title.$count") or die "can't open";
    $count++;
    print OUT "$content";
    close OUT;

}
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