How do I change css for h1, h2, h3 font sizes

Hi,

I've got a new installation of easyblog on J3.3. But the layout is not consistent with my main template. I've searched for answers but found none that suit. I'm looking to change css for h1, h2, h3 font sizes. But I see answers which point to files in paths which I do not have. Also, although there is lots of documentation on lots of topics, I don't see anything which points me in the right direction. Can you please tell me how to change the fontsize of the headings in easyblog?

Also, the blog titles seem to be h2, as do the blog headings within the posts, but both are different sizes. I'd like them to be the same, if possible.

The url for the site is http://cgcf.ie/new2/index.php/en/blog

Thanks