I've uploaded an image on my page, how do I change the size?

Once your image is inserted in the page content editor, click on the image to select/highlight it, click (and hold the click) on either of its corners, then drag-and-drop the image to your desired size.

Another way is to click on the image to select/highlight it, then click on the icon 'Insert/Edit Image' in the page editor toolbar. In the pop-up window that opens > 'General' tab, you can change the size of the image from the 'Dimensions' fields (for the width and height of the image).