It seems that you may not be familiar with the basics of how components work in Ossn as Z-Man said. It's rather easy to get all blogs, just look at the functions in components/Blog/classes/Blog.php. There are built in functions to get all blog posts site-wide as well a function to get all blog posts by user.

I already understood and read the manuals. I will try to make my own plugin. Thanks for the advice.

Looks like you didn't have a look at the example components I mentioned?

Please do so. And aside from that please study the complete Ossn documentation, as you will learn that Ossn is based on a modular concept. 'Modular' means that changing or adding functionality has to be achieved by creating your own new component (module) instead of altering anything existing.

So first of all: Don't touch the Blog component since the next update will overwrite all that you would have changed.

Next, create your own component and as a first exercise just apply that hook the way I said and a function of yours which will simply display a 'hello' on the right sidebar.

In file
components/Blog/ossn_com.php
in lines

case 'all_blogs_by_date':
						$blog = new Blog;
						$blogs = $blog->getBlogsByDate();
						$count = $blog->getBlogsByDate(array(
							'count' => true
						));
						$title               = ossn_print('com:blog:blog:all');
						$contents['content'] = ossn_plugin_view('blog/pages/all_blogs_by_date', array(
							'blogs' => $blogs,
							'count' => $count,
							'page_header' => ossn_print('com:blog:list:sort:by:date:page:header')
						));
						$contents              = ossn_set_page_layout('newsfeed', $contents);
						echo ossn_view_page($title, $content);
										

tried to apply

ossn_add_hook('newsfeed', "sidebar:right", $contents);

Not work.

tried to output in the template (themes/goblue/plugins/default/theme/page/layout/newsfeed.php)
this file
components/Blog/plugins/default/blog/pages/all_blogs_by_date.php
Not work. Please, what am I doing wrong?

Some so-called 'hooks' are responsible for what is going to be displayed on the right sidebar.
You may add your own hook like

ossn_add_hook('newsfeed', "sidebar:right", 'YOUR-OWN-FUNCTION');

See OssnAds and HTMLSidebar components for examples.

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