Struggling with the idea of keeping sins private

Salaam, this might sound a bit naive, but I'm honestly confused about how strictly we're supposed to conceal our sins. I get that we shouldn't boast about them, but does it mean I can't even mention I did something wrong and need to make tawbah, without going into specifics? Or is the rule that absolutely no one should know I slipped up? I've only been Muslim for two months, and the brothers at the mosque are the only Muslim contacts I have, but we're not close enough to talk about such personal stuff yet. Sorry if this is a basic question, just trying to understand.