Can Anyone Help Me?

I need to buy Scars of abyss where can i buy it? -.-; since its just the new one showing at the thingy

You can buy it right from Playonline.
They have it advertised on the main FFXI login screen where you hit "Play". If you want to buy a specific one, you should be able to find a submenu there to purchase specific expansion packages.

awwww i cant find it ... lol...

There should be a menu on the left side below "Play" that has optional or expanded services. Which will give you a registration code for the chosen expansion. Since "add-on" expansions are already pre-installed via standard FFXI updates, you won't need to install anything, simply registering the code they give you after purchase enables you to access the content therein.

Look for (content id?)
registration code purchases and option is nearby to purchase additional

It's under Special Services or something like that. It's in the menu on the title screen where it has the Hero's one.