Here's one way. Note there were some commas missing from your data structure.

Have a look at perldsc - complex data structures 

#!/usr/bin/perl

use strict;
use warnings;

my %HOH = (
  Pegname1 => { 
    section1 => { val1 => 'Value 1' },
    section2 => { val2 => 'Value 2' },
    section3 => { val3 => 'Value 3' },
  },
  Pegname2 => { 
    section1 => { val1 => 'Value 1' },
    section2 => { val2 => 'Value 2' },
    section3 => { val3 => 'Value 3' },
  }
);

# question 2 - add a new value
$HOH{Pegname3}{section1}{val1} = 'Value 1';

# question 2 - add a new record
my $record = {
    section1 => { val1 => 'Value 1' },
    section2 => { val2 => 'Value 2' },
    section3 => { val3 => 'Value 3' },
};    

$HOH{Pegname3} = $record;

# question 1 - traverse the data structure
for my $peg (sort keys %HOH){
  print "$peg\n";
  for my $section (sort keys %{$HOH{$peg}}){
    print "\t$section\n";
    for my $val (sort keys %{$HOH{$peg}{$section}}){
      print "\t\t$val\n";
    }
  }
}

__DATA__
---------- Capture Output ----------
> "C:\Perl\bin\perl.exe" _new.pl
Pegname1
    section1
        val1
    section2
        val2
    section3
        val3
Pegname2
    section1
        val1
    section2
        val2
    section3
        val3
Pegname3
    section1
        val1
    section2
        val2
    section3
        val3

> Terminated with exit code 0.

[download]
Update: Added 'add new record'
Update 2: Forgot to update ouput

In reply to Re: hash inside hash inside hash by wfsp
in thread hash inside hash inside hash by Anonymous Monk

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