How to add something like this?

Beside what Box where? A little more detail and a link to your site would probably help.

The Box where you write your Email.

I am working on Localhost right now But using the same Template as solaf.cc

Thanks ??

Where you write your email for what? I’m sorry but without being able to see this box in the context of a live page, it’s hard to offer any specific help.

I already posted you the Page where you can see everything: https://www.solaf.cc/

It’s a Feedburner he added a small Icon to the right, you can see it here
https://www.f1zone.net/up/img44/9471/17letter.png

How can i make the same one?

Is https://www.solaf.cc/ your site? If not, try posting a link to your site.

for god sake read my posts, I TOLD YOU THAT I AM USING THE SAME THEME ON A LOCAL SERVER.

No one can help with your problem by looking at another site. Even if it it is using the same theme as you, there is no way to determine the level of customisation carried out on a 3rd party site. So either get your temper under control or learn how to sort your own problems out.