You can easily change the size of an image you added with the editing toolbar by dragging the image's borders.
(Note that thumbnail images in a gallery cannot be resized.)
To change the size of an image:
YSS Selected Image
YSS Image Resize Handle
YSS Repositioned Image Resize Handle
YSS Resized Image
Hint: To avoid distorting your image, click and drag the corner of the image inward or outward. Moving the corner instead of one side of the image will help you preserve the ratio of the image's height and width, so the only change to your picture is its overall size.
Please note that changing the dimensions of an image on your page does not affect the image's file size. If your image has a very large file size, it still might take a long time to appear on your page. Learn how to save your image with a smaller file size.