How to oranize the structure of the posts?

Without looking at the code, you most likely will have to switch out the_content(); for the_excerpt(); https://codex.www.ads-software.com/Function_Reference/the_excerpt

Make sure that you create a child theme first so you don’t lose your custom code if you update the theme. https://codex.www.ads-software.com/Child_Themes

Hi graphical_force, thanks for helping me. I’m looking for something like this: https://dosomethingcool.net/ . I want the posts like that, is there anyway that I can get it like that by just changing the theme?

Yes, and the answer was in the response I already gave you. https://codex.www.ads-software.com/Function_Reference/the_excerpt

Thank you, but how would I do it? Ay the end of the post I put this?

function new_excerpt_more( $more ) {
return ‘ Read More‘;
}
add_filter( ‘excerpt_more’, ‘new_excerpt_more’ );

Can you post the code from your theme where you would like it changed?

Sorry, my skills are limited in this area. I want to change it only in the index page, where the posts are, nothing else.

I don’t know where is the code, do you mean this?

/*
Theme Name: Kirumo
Theme URI: https://kirumo.johnregan3.com
Author: John Regan
Author URI: https://johnregan3.me
Description: Kirumo is a simple reponsive blogging theme with an elegant sliding mobile menu.  This theme supports custom background colors and images, as well as a custom accent (link) color.  One if its unique features is a full-width page template with a horizontal row of three widgets below.  It also features formatting for all post formats, RTL layouts, and vertical featured images.  Download Kirumo and take it for a test drive!
Version: 0.3
License: GNU General Public License v2 or later
License URI: https://www.gnu.org/licenses/gpl-2.0.html
Text Domain: kirumo
Domain Path: /languages/
Tags: black, custom-colors, custom-header, custom-menu, dark, featured-images, fluid-layout, full-width-template, gray, left-sidebar, post-formats, responsive-layout, right-sidebar, rtl-language-support, sticky-post, threaded-comments, translation-ready, two-columns, white

Kirumo WordPress theme, Copyright (C) 2014 John Regan
Kirumo WordPress theme is licensed under the GPL.
Genericons font is licensed under the GPL and is available from https://genericons.com.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2, as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

Kirumo is based on Underscores https://underscores.me/, (C) 2012-2013 Automattic, Inc.

Resetting and rebuilding styles have been helped along thanks to the fine work of
Eric Meyer https://meyerweb.com/eric/tools/css/reset/index.html
along with Nicolas Gallagher and Jonathan Neal https://necolas.github.com/normalize.css/
and Blueprint https://www.blueprintcss.org/
*/

@import url( "inc/css/base.css" );
@import url( "inc/css/mobile-menu.css" );
@import url( "inc/css/kirumo.css" );
@import url( "inc/css/structure.css" );
@import url( "inc/css/genericons.css" );

No that is not it. That is the css file. Most likely it is in this file: content.php

I’ve not installed this myself to test so you may need to experiment with it.

You can customize the WordPress read more or use a plugin.
https://codex.www.ads-software.com/Customizing_the_Read_More

Thanks kmessinger, I’ll read everything.

graphical this is the code in content.php

<?php
/**
 * @package Kirumo
 */
?>

<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
	<header class="entry-header">
		<h1 class="entry-title"><a href="<?php the_permalink(); ?>" rel="bookmark"><?php the_title(); ?></a></h1>
	</header><!-- .entry-header -->
	<?php if ( has_post_thumbnail() ) {
		the_post_thumbnail( 'large' );
	} ?>

	<?php if ( is_search() ) : // Only display Excerpts for Search ?>
	<div class="entry-summary">
		<?php the_excerpt(); ?>
	</div><!-- .entry-summary -->
	<?php else : ?>
	<div class="entry-content">
		<span class="genericon genericon-standard post-format-icon"></span><div class="post-format-content"><?php the_content( __( 'Continue reading <span class="genericon genericon-next"></span>', 'kirumo' ) ); ?></div>

		<?php
			wp_link_pages( array(
				'before' => '<div class="page-links">' . __( 'Pages:', 'kirumo' ),
				'after'  => '</div>',
			) );
		?>
	</div><!-- .entry-content -->
	<?php endif; ?>

	<?php get_template_part( 'content', 'footer' ); ?>
</article><!-- #post-## -->

Go ahead and apply some of the information in the link provided with this code and see if you achieve your goals.

I’ve been trying to insert these codes:

function new_excerpt_more( $more ) {
	return '[.....]';
}
add_filter('excerpt_more', 'new_excerpt_more' 200);

or

function custom_excerpt_length( $length ) {
	return 20;
}
add_filter( 'excerpt_length', 'custom_excerpt_length', 999 );

at the end of function.php but it doesn’t do anything…

All that code does is change the length of the excerpt. You need to concentrate on where you call the code.

In this case if you want to show the excerpt you need to have the_excerpt(); in the code instead of the_content();. Now look at the code that you posted and see where you may be able to do that at and see what results you get.

graphical you are a great teacher, but I need to study math and I’m spending too much time in something that I don’t know yet, I haven’t even look at the widgets of the web, can you just help me with this now please.

Can someone help me please? I’m not a programmer, I just want my blog to post my stuff.

All graphical_force, and any volunteer here, can do is give advice. If you don’t have enough time to spend implementing the advice given, or need extra support in doing so, then you may need to consider hiring someone.
If that’s not an option then you need to continue waiting for support here, without bumping.