Clicking the insert/edit image button
will open the following window:

Click the image browse button ![]()
From here you can:

Once you have made your selection, just add an image description and click insert.
Top tip: Always try to use images that are already the correct dimensions.
Need help with this? Check out Resizing and Cropping Pictures.
This is written into the code 'behind-the-scenes' and is used both by search engines and text readers (used by visually impaired viewers to read the site) so, although it is optional to include a description, it is highly recommended for obvious reasons.
Keep it short and simple and if it is more than one word, try to use keywords.
E.g. a landscape gardener may have a photograph of a garden they have created. The image description could be.... Photo of a water feature and patio in a landscaped garden
Alignment - determines how images and text are aligned with each other.
Dimensions - You can manually edit the dimensions of your image, however we recommend using images that are already the correct size.
Border - Applies a border around the image, the border width should be determined in pixels. A preferred method of applying a border would be to use the attributes button.
Vertical and Horizontal Space - Sets a space or gap (in pixels) around the image. Again, we recommend using the attributes button.