AppleID in AppStore

I have a macbook air, and I want to download something from the app store, but it's not happening because there's something wrong with the AppleID.
I have an appleID, but every time i try to download something, the app store tells me that my apple id hasn't been used in the app store yet, and that I need to check my settings. But I can't do that, because I get the same notification when I try to do so.

What's wrong and how can I fix it?

Thx!