I Tkx rather than Tk but the ideas are the same.

As kcott taked about i use grid on the frame parts, and pack the frame into mainwindow 

use strict;        
use warnings;        
use Tkx;        


my $mainwindow = Tkx::widget->new(".");
$mainwindow->g_wm_geometry("600x150");
$mainwindow->g_wm_title("Window");

# Disable the window Resize
$mainwindow->g_wm_resizable(0,0);

# text variable
my $label_firstname;
my $entry_firstname;
my $label_lastname;
my $entry_lastname;
my $label_loginid;
my $entry_loginid;
my $button_add;


# make a frame and pack it into mainwindow 
my $w_frm = $mainwindow->new_ttk__frame();
$w_frm->g_pack(qw '-fill both -expand true');

# make parts and grid them into frame 
$label_firstname = $w_frm->new_label(-text => 'Firstname:')
                         ->g_grid(-column => 0, -row => 0, -sticky => 
+"we");
$entry_firstname = $w_frm->new_entry(-width => 35,-text => 'Firstname'
+,-justify=>'left')
                         ->g_grid(-column => 1, -row => 0, -sticky => 
+"we");

$label_lastname = $w_frm->new_label(-text => 'Lastname:')
                         ->g_grid(-column => 0, -row => 1, -sticky => 
+"we");
$entry_lastname = $w_frm->new_entry(-width => 35,-text => 'Lastname')
                         ->g_grid(-column => 1, -row => 1, -sticky => 
+"we");

$label_loginid = $w_frm->new_label(-text => 'Login ID:')
                         ->g_grid(-column => 0, -row => 2, -sticky => 
+"we");
$entry_loginid = $w_frm->new_entry(-width => 35,-text => 'loginID')
                         ->g_grid(-column => 1, -row => 2, -sticky => 
+"we");

  Tkx::MainLoop;

[download]
you should be able to translate into Tk

In reply to Re: how to align the label and entry text box in my tk GUI by huck
in thread how to align the label and entry text box in my tk GUI by fsmendoza

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.