Childnet have produced a leaflet for parents to support children and young people to stay safe online https://www.childnet.com/ufiles/Supporting-Young-People-Online.pdf
In addition to English, the leaflet is available in a range of other languages https://www.childnet.com/resources/supporting-young-people-online
Better Internet for Kids has sites for all European countries: https://www.betterinternetforkids.eu/sic