There are two main blogging platforms.
WordPress is owned by Automatic (which I would recommend over all others).
Blogger is owned and managed by the Google organisation.
Both platforms offer users the opportunity to set up a blog free of charge.
This page provides a link to information on setting up both WordPress and Blogger.
WordPress.org versus WordPress.com
If you search WordPress you will discover that there are two apparently distinct entities. WordPress.com and WordPress.org . Both belong to the same company.
Setting up a blog on WordPress.com is the easiest option for beginners. The hosting and managing of the software is taken care of by the WordPress team and you get a blog address that goes http://www.yourblogsname.wordpress.com
WordPress.org allows you to download the blogging software to install on your own server meaning you can have a blog with the address http://yourwebsite/blog without the word WordPress included. One of the main advantages of WordPress.org is that it enables the user to install additional functionalities (plug-ins) developed by other technical savvy users.
.com or .org? Not sure which to choose, but desperate to start blogging?
Choose the easy option and set up a blog on WordPress.com because you can always export all content over to a WordPress.org blog at a later date. The important thing is to start blogging great content as soon as possible and begin building your audience online.
To set up a WordPress.com blog go to this page http://learn.wordpress.com/get-started/ and follow the blow-by-blow instructions.
For further information on the differences between WordPress.com and .org including advantages of one over the other go to http://en.support.wordpress.com/com-vs-org/
To install WordPress.org on your server go here http://wordpress.org/ but remember you will have to be a little technically savvy, or have a friend who is.
You will be required to set up a Google account in order to set up the Blogger blog.
Blogger provides a similar service to WordPress.com but there is not an equivalent of WordPress.org software that can be downloaded on to your own website with all its attendant advantages.
To create a Blogger blog go to www.blogger.com