Click on the image in the editor that you would like to replace, and then click on the delete image icon. Click on the add an image icon next to the upload and insert text located above the formatting toolbar. A popup dialogue box will appear and you will have the option to upload an image from your computer, a webpage or URL, or an existing image from your Media Library. To upload an image from your computer, click on the select files button, then select the file you want to upload and then press open or select. Once it is uploaded, you can create a title and other info. Configure the options for how you would like the image to appear, and then click the insert into post button. Click on the preview changes button before publishing or click the publish button to publish the changes.