Stack Overflow certainly is useful. There is a wide variety of users with different areas and levels of expertise. If you have a good question, I'd say you're almost guaranteed a decent answer and perhaps some additional comments.
It's a tricky beast however. Asking questions is difficult. Asking good quality questions (the type we like to see) is even harder. So if you're not entirely clear on what you want to ask, or even if you have difficulties formulating your questions, Stack Overflow might seem harsh from time to time. But it's not personal. All we're trying to do is protect the quality of the site. That's what brings in the users and letting it slip would cause harm.
So what can you do to improve your questions? You could read some of the excellent advice that is available at various locations. On our own site the Help Center contains a wealth of information. Take some time to read through the various topics on how to ask a good question. And then there's Jon Skeet's blog post on asking the perfect question.
And language counts as well. Is English not your first language? Then practice. Read some of the good questions and great answers. Read literature. Talk to people whose language skills are better than yours. Look at the edits of your posts that have been made by others. Try to understand why they did what they did. It will help you formulate your questions, which will in turn attract answers.
Is reading all that necessary? If you have a hard time getting positive responses to your questions, the answer is yes. Should you have a particularly difficult time understanding why a certain questions is downvoted, feel free to come to Meta. Give us a link to the question, tell us what you exactly don't understand about the voting by the community, and we'll gladly explain to you what the problem is. If you're genuinely willing to learn and understand, you'll find plenty of people here who will try to help you out.