I want this theme.

How can I make my forum like this ? http://www.duelacademy.net
That theme, I want.

Hello,

Here's a link where you can find several themes, you'll surely find one that suit your needs : http://en.hitskin.com/

You can't have another forum's theme if its admin didn't uploaded it on Hitskin.

I can't find something like that in hitskin. Any other way?

No, unless creating your own one

That was a skin created by Amy Cool and graphics from Anzo. As Leloo said, it'd be better to create your own.

Here's a guide if you're planning to create one:
https://help.forumotion.com/t47086-skin-style-and-aesthetics-guidelines

Good luck