Welcome, you seem like a nice guy. Say what you think and I'm sure you'll be fine. The closest thing to guidelines are at: http://ycombinator.com/hackernews.html

To quote PG: "The focus of Hacker News is going to be anything that good hackers would find interesting. That includes a lot more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity.

It may be easier to say what that doesn't include. It doesn't include most stories about politics, or crime, or sports, unless they're evidence of some interesting new phenomenon. It doesn't include videos of pratfalls or disasters, or cute animal pictures. Basically, if they'd cover it on TV news, it's off-topic."