I am new to Episerver.
Were should I look for more information on validating editors/backendsusers inputfields.
I need to make som validation on this:http://screencast.com/t/si27US3Fr So that if the user check the checkbox the other fields in the formular must also be filled to validate.
Have a look at writing custom validation attributes.
You could write your own custom validator by implementing the IValidate<T> interface