To create a blog with the default Joomla CMS,
1) Add a new item to a menu.
2) Select articles > category blog layout or section blog layout.
3) Add appropriate figures for leading, intro, columns, links.
You can experiment with these numbers until you have the desired amount of leading articles, columns and links. With a blog layout, you have all articles from a section or category accessible of the first page. This is a decent looking layout and each page is very customizable with the content editor.
Another option for adding a blogging component is to download a blogging component, install it, configure the backend parameters and edit php/css files to customize it (if necessary).
There are many blogging components such as myBlog, jaggyBlog, EasyBlog, Wordpress Blog for Joomla, RSBlog and Smart Blog. Some are even free.
Personally, I have taken a liking to myBlog and JaggyBlog. MyBlog is a little more expensive, but integrates well with JomSocial and JomComment. JaggyBlog is a steal for the price, and you can set menu items to only show entries for a specific category, or all posts.
A downside to blogging components is that you may not have the control you like over sidebar categories. A way around this is to use custom menus with custom article links. This way, you can make custom article groupings; even to those which exist in different sections or categories.
Adding Wordpress to Joomla
One option to add a blogging platform is to install or FTP Wordpress into a subfolder within the root Joomla directory. With this option, you can use the existing database or create a new database. If you use the existing database, Wordpress will use a different database prefix. Using a separate database will help lighten the load from the Joomla database. This method of using Wordpress works fine if you don't need the blog to be integrated into the Joomla CMS; such as with a member site; or with various blog users. Alternatively, if only bloggers are hired, using the separate installation keeps them only where you want them.
To access the Wordpress pages, you simply use an external link in the Joomla site to a page in the Wordpress installation.
When a separate Wordpress installation is used within Joomla, the Wordpress plugin 'page-links-to' allows you to create the exact menu you had in Joomla; even pointing the home page back to the Joomla home page. However, the templates are different. If computer generated software like Artisteer was used to make the Joomla and Wordpress templates, templating could be rather fast; especially if they were not edited afterwards. If they are edited, both should be changed accordingly to make the match.
Now, you can blog in Wordpress and link to this blog from Joomla for SEO purposes. All pages in the main menu will link to Joomla pages and all posts in the Wordpress installation can be assigned to new categories.
If you have familiarity with Wordpress, adding it to a Joomla installation could be rather painless. But, if you are new to Wordpress, you must be prepared to learn a few things in order to manage the blog effectively.
The same approach to using a Wordpress blog can be applied to other blogging platforms too; such as a Codeigniter blog application, or php/mySQL blogging software.