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

use constant {
    WORD => 0,
    TYPE => 1,
};

my @annotations;

while (<DATA>) {
    my ($word, $type) = split;
    $type =~ s/.-*//;
    push @annotations, [ $word, $type ];
}

print '<text>';
print join ' ', map $_->[WORD], @annotations;
print '</text>';
for my $annotation (@annotations) {
    print '<annotation>';

    print '<type>', $annotation->[TYPE], '</type>';
    print '<text>', $annotation->[WORD], '</text>';

    print '</annotation>';
}


__DATA__
how B-NP
are I-NP
you I-NP
[download]

how would it be if my input was

how  o  B-NP
are   o o
you   o  I-NP
[download]

now i need annotation tags only for those words which has B-NP and I-NP in the third column

I pressed the wrong button and shrunk the code accidentially. It still should do what you want.

use strict;
use warnings;

print "<text>",join(" ",map{/^(\w+).*?(B-NP|I-NP)?$/;
$a.="<annotation><type>NP</type><text>$1</text></annotation>\n"if$2;$1
+}<DATA>),"<text>\n$a"; 

__DATA__
how B-NP
are
you I-NP
really
[download]

The "NP" in your desired output is taken from which line of your input?

the full output i want is as shown

<text> how are you> </text> <annotation><type> NP</type><text>how></text></annotation><annotation><type>NP</type><text>are</text></annotation><annotation><type>NP</type><text>you</text></annotation>

so the type should contain the 2nd column of corresponding text in the tab seperated input file

Ah! Then this is how I would do it:

1. Loop over the lines of your input.
2. Extract all word characters from the beginning of the line for the text field.
3. Extract all word characters at the end of the line for the type field.
4. Independently build the initial <text>...</text> and the <annotation>...</annotation> parts by adding them to two strings.
5. After the loop print the two strings into an xml file.