Just type it into the big "Ask a question" box at the top on any page and press the ask button or hit enter. To begin with, enter 1 or 2 words of your topic, then press ask. This will display questions with those words in it to see if questions on the same topic have already been asked. If you desire you can enter a category name on the box to the right, but that's optional. If you want to add a category at a later time you will have that option once you've made the question.
On this site all or nearly all articles are based on a question. Clicking on Ask creates a new article with the title being your question.
Then you can click on "Answer Question" if you want to answer your own question. If you feel the need to add additional details to your question, you can use the discussion page.
Make sure your question is suitable for Wikianswers.
If you accidentally add a misspelled question, you can rephrase it or delete it.
See How can I get my question on Wikianswers answered more quickly? for advice on getting answers.
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