Hello,
Is it allowed to use Sanserifing font for commercial use, for post cards? If yes do I have to write what kind of font it is? Please help!

"Font released under Creative Commons Attribution 3.0 Licence." it says. When you don't know what that means you might have asked Him who watches over all of us and knows everything about all of us. His very first hint is this: https://creativecommons.org/licenses/by/3.0/

Was that too difficult? OK, there is a spelling error. But that one was easy to correct, right?

Ok, but there is information that I must put information about author? I am not sure. This is a little bit difficult. There is not space for this one the post card. What exackle I must write on the project? I would like to be sure.

Under this license you do not have to credit the author of the font.

So It means I don't have to write any informations? Sorry but I don't what to make mistake.