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Go to your post and on the bottom right corner of the page under "Promote", you should see "edit" beside the "reply" button.
Click "edit" to make changes to your post. You only have access to edit within 7 days of posting the article.

To insert pictures in "edit" mode, just click on the picture icon right beside where you select font sizes, enter the link to the picture and you're done.

Thank you kind sir!