It's not necessarily, rude, but it can be very difficult for other users of the community to understand.
On any sort of network that uses a single-language, such as Stack Exchange, posts that don't demonstrate a native proficiency of the language can often get mixed reception. What this means, is that some people will appreciate the post, whereas others will not.
Posting, therefore, isn't rude - it's actually what these communities are designed for. They want you to ask questions. What is rude, is if you don't make an effort to contribute a high-quality question.
In some cases, the lack of language proficiency can make the question viewed as a low-quality question (though I personally believe that on SE, it wouldn't make it low quality). What you need to do, is improve your question, and try to do it before you post it. Never be afraid to ask for assistance!
If your community has a chatroom, such as Stack Exchange, then ask in that chatroom how to best phrase your question. If you don't get much feedback there, then post your question. Be sure to stick around in the moments after you post it, and to check back regularly to see if any users post feedback.
But otherwise, always post your question! You post a question to learn. The fact that you have learned English to participate is also very admirable. Keep it up!