It's possible to send to your site images that are on your hard drive, creating your personal archive of images that is organizable in folders and sub-folders (the same method used to organize the pages of your site in sections and sub-sections).

Go to the image folder (or a sub-folder you created before) and click on the button (add image) located on the bar.

If you have the address (url) of an image you can use that directly.

To insert the images loaded on the server or included in the common library, you must first have created a new page and inserted a block that allows an image inside of it.
Then by double clicking on the gray "placeholder" image (the one shown here on the right) you'll be able to choose which photo will take its place.