There are many benefits to
"Registering" rather than just logging on as a Guest, and it's easy. Just click on Register Button at the top of the page.
By registering:
All posts you make will automatically have your name filled in, and you can assign a small picture called an Avatar to make yourself unique.
You will be able to see which posts are new (there will be a marker next to posts that says
"NEW").
You can get email notification of replies to your posts.
You can send private messages to other members.
No one will be able to post using your name (you can "secure" it so that no one else has it!).
There are many more reasons to register that you'll see once you've done so, but there are just too many to list here.
Also, as a Registered Member, you will have access to "Member Only" areas (which I ahven't setup yet, but maybe later)
I strongly encourage you to register for any board you are active on, especially This One