Ask HN: How to Security Audit for Noobs?

Hello, I started working on a side project during my free time, and I was thinking of converting it into a side hustle. The side project involves ensuring data-integrity and ownership of a file by storing metadata about it in blockchain (the actual file isn't stored). I was thinking of letting others use it, but what if it's not secure enough? What if people use it and something happens, would I be in hot water?

Once I develop the project enough, I do plan to make it open source, and only after that I would launch. At least that's the plan. I was wondering how to do good enough security audits on your own when the software is finally built. As I am merely a sophomore in college, I can't afford professionals for the same.

What do you guys suggest?