White side

What goes wrong. When I typed in a product in my cateroi and click save, my side get white and I can see all komandoerne as link. please How can I fix it?

That means that the CSS could not be loaded on that page.
I don't know why though.

Do you have an error message at the end of that page ?
If not, could you increase the "error reporting" option of the configuration of joomla and try again ? That might give some errors enabling us to understand why you have the problem.