When you first post your link, it appear on /newest if you post at a busy time it might fall off the first page of /newest very fast.
However, if your post gains enough tracking (comments/upvotes) it goes to the front page.
Most people have lots of links with no votes at all. Don't expect your link to make it to frontpage.
You gain karma when people interact positively with your content (submissions and comments) you lose it when people react negatively (downvoting, probably flagging). You lose more from a downvote than you get for an upvote.
The thing is self-promotion is allowed on HN, even explicitly so (see: Show HN). But that's not, as I understand it, how the powers that be want people to primarily conceptualize HN. First and foremost, it's a platform for, um, what's the phrase, "satisfying your intellectual curiosity" or whatever. The self-promotional stuff is a side-bar to that, not the headline on the marquee sign so to speak.
Net-net... you have a new account, your thing got auto-flagged or whatever. The solution, as others have pointed out, is just to email the mods (and/or hope somebody will "vouch" for your post, which apparently they did). Beyond that, make sure to read the site guidelines[1] and FAQ[2]. Most of what you need to know is there.
It’s an audacious plan, I’ll grant you that.