Once you have it, click the "Add Picture" button.

This will stick the photo at the top of your entry, and depending on the size, will wrap the surrounding text around it.

Slightly Harder Way (that gives you more control): Refer back to Step 4 above: After you upload the photo to File Manager, right-click the file name and copy the photo's address (depending on your browser, it will be either "Copy Shortcut" or "Copy Link Location"):