I want to put <h1> to my blog but do not know if you can do this in Atahualpa Theme Options -> Add HTML / CSS inserts or in style.css

Look in the source code and tell me why <style type="text/css"> body look so bad. What should be changed?

H1's are automatically put in the page. On a 'page' page it is the name of the page and on single post pages it is the post title.

you can change this in the theme options or use a SEO plugin to change this.

I use All in one SEO plugin.
Have you looked in my source code?
I want to put this code in the source code of my blog.

<h1><a href="http://www.reclame-tv.ro/">Reclame Tv</a></h1>

Where do you want to put it? there is an option to overlay the blog title on the header image or display the blog title in the logo area and they are automatically made links. Try those options