I don't understand what the problem is. You can get reputation when people upvote your posts. These posts can be
Questions: each upvote will gain you 5 rep.
Answers: each upvote will gain you 10 rep.
So, the better way to gain reputation is to answer existing questions. There are new ones coming in every day, why don't you simply go and answer them? If your answers are good, people will upvote and you will get the reputation you covet.
While the reputation system does indeed impose restrictions on new users, there is no restriction on posting new content, neither questions nor answers. As explained here:
What is asking and answering questions? The most basic privilege of all -- the right to ask a question, and the right to contribute an answer. This is generally available to everyone, regardless of reputation level.
So, go forth and answer!
It is true that you need 5 rep to answer here, on http://meta.askubuntu.com.
This is not the case for the main site, http://askubuntu.com and, anyway, answering here does not gain you reputation, so that's not what you're after. The Meta is where we discuss issues about the main site, not where we post and answer questions about Ubuntu.