i cant log game and support say clean browser cache but i am french where can i clean browser cache and how please

 Cleaning your browser cache is something that you ought to be able to do anyway, and do often,even if you are not playing this game.

 Assuming you are using a computer ,I hope this is enough information to find the cache.

Its likely to be at the top of the page on the right hand side where you should find many symbols for clickable links.

In my case its the last one and either lll , or ..., click on this to open it ,find the browsing history
open it and delete it, it may give you the exact instructions to do this. 

You may have, should really have a  program that will protect your computer and do this for you.