Hi Tiocaro, If there is a an image on a page already that you would like to change you can click on the existing image then the small circle on the bottom right to take you to the image file details page and then click on "Upload a new version of this file" which will allow you to select a new image.
If there are any countries you want me to do the navigation tree for I would be more than happy to do so.
Please do note that the site is an English language site and pages and text must be in English. We might in the future look at translations but for now please can you create pages in English.
Your contributions are most appreciated.