There are Two things you need to start a WordPress blog:
1) A Domain name (this will be the name of your website or blog i.e http://hostonnet.com).
A web host, or web hosting service provides the technologies and services needed for the website or webpage to be viewed in the Internet. Websites are hosted/stored, on special computers called servers.
You can register domain name and hosting service from HostOnNet.com
Once you got domain name and hosting, you just install WordPress for free and start blogging!
How to Add a New Post in WordPress