Changing the nameservers is something you can easily do through the control panel of any website registrar. In effect it changes the address of the server where your site actually resides.
You might choose to do this if you register many names as I do and can get a better price somewhere in particular. For example I"ve registered many of my sites with Cheap-DomainRegistration.com which I"ve found through experience is substantially less expensive than some other registrars I"ve used.
Hosting Your DomainThere are quite a few quality companies with which to host your blog. I can recommend several that I"ve used for a number of years and continue to use. Each makes it very easy to host your Wordpress blog, offer reliable hosting and provide excellent customer service.
Here they are:Hostgator
Why Use WordPress?
As I mentioned earlier I recommend you build your blog using Wordpress. This is used by millions of bloggers and a robust community of users and developers has grown up around it.
It certainly isn"t the only blog platform out there, but I can"t think of a single reason why I would choose to go elsewhere.