Adding a picture to a question or answer is now as easy as …
Clicking the Insert Image
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Selecting an image from your computer, or the web
Clicking Upload
Note: you need to be registered member in the site with at least 10 reputation in order to gain the privilege to use this feature.
Source: How to upload an image to a post?
If you don't have at least 10 reputation, don't worry, you can upload your image to imgur for example and insert in the body question the link to the image. Someone who has enough reputation will most probably edit your question and will add the image correctly (of course, if the image is ok).