Hi all I'm learning spanish and I'd just like to say hello and see ya in the posts!
Sometimes people down vote posts that just say "hello" because they feel like they take up too much space and they just want to discourage that sort of thing. I mean can you imagine if everyone who joined today or this week put up such a post? Ay, ay, ay! Then all the posts would be like that and that would be too much! So, if thousands of people abstain from that I think people hope everyone will. :) Just my guess.
Perhaps a better way to introduce yourself and meet people is to post on already existing discussions or to post a question people can help you with. Then you would see real interaction and really have fun! A post that just says "hello" is sort of like waving to people from a car driving by. It might be fun in the moment, but...if you stop the car and really talk to people you can get to know them better and vice versa. So, instead of just "hello" perhaps ask people why they are studying Spanish and then join the discussion and tell the readers why you are. :) Good luck!