To add an image to an answer, simply click on the image icon in the answer's toolbar:
You may then choose to either use an existing image on the web or upload an image from your own computer:
1) Adding an image that's already on the web:
In the URL dialog, simply enter the target URL.
2) Uploading an image from your computer:
In the 'Image Properties' dialog, click on the "Upload" tab and upload desired image.
There is no need to enter the image characteristics, as this is done automatically.
You can also adjust the size to the image.
When finished, click on the "OK" button.
To learn how to add a link to an image, click here.