If you want a regular .com name, you will need to buy domain name and then redirect it to a free host. Or, you can simply use a free web service that uses a .com extension.
A blog does just about the same thing. To learn to make one try going to Ask or searching online. At a search engine, you can type in 'How to make a blog'.
Wordpress is a free blogging service, though you can pay to upgrade it with custom themes. If by chance you decide to upgrade to a traditional website and pay all that money, then you can export your data from Wordpress and install the Wordpress site code on your site. Then you can import your data from the Wordpress site to your own self-hosted blog that is on the same server as the rest of your site.