Salla - it's not complicated, honestly ! The most difficult thing is working out what all these new terms mean (like upload, copy and paste lol)..
1. Register with one of those sites mentioned (username and password, usual stuff).
2. Upload (which just means copy from your pc to that site) the relevant picture, using the upload and browse buttons.
3. Copy the url/img reference (which will just be a name that the site has given to your picture) and paste it onto your AnswerBank response.
4. Click on AnswerBank preview button to make sure the link works.
5. Any problems, just email me !
PS To quickly copy something, just highlight it and press the Ctrl and C keys together. To paste something, just press the Ctrl and V keys together.