When uploading files, the files are stored physically on the web server, in this folder (relative to the top folder of Opinio):

upload/<user-id>

Replace the user id with your own user id (see user profile). If you are storing your files in the common-area, they will be accessible to all users, and stored in the folder

upload/<common>

If you for some reason want to refer to an image by manually inserting a link to it, you can type the following in the question text of the survey (or any other text, like header/footer, text before question, etc), if your user id is 10, and the name of your image is "myImage.gif", for example:

<img src="upload/10/myImage.gif">

You can find your user-id when editing your profile. Select "users" from the main menu.