@Ferret@Gantic lets say theres a jpg photo in c:\ which is called "asdf". can i upload it by clicking on the image adding button and typing "file:///c:/asdf.jpg"?
Please don't tag admins for such trivial questions.
No you can't. File paths within your computer are not the same as internet links. You will have to find an image hosting site like imgur.com, upload the picture from your computer and copy the link there. This link can then be used for the 'Image' button.