First of all, in your case the problem is your reputation. As a new user, you cannot post pictures. We will update the posts for you, until you gain the privilege to do so.
The simplest solution, once you can, would be clicking the img button on the editing form, or using the shortcut it shows (Ctrl+G):
This then prompts you with another mask which allow direct upload and linking and thus automatically inserts the necessary code:
If you do not want to use this mask, however, you can click the Images button on the help bar, which shows the markup:
