by using your mind... like someone told me "Mind over Matter" is the key to magick and everything that happens in your life and the people that are close to you...
Secret room...harry potter?
Oh boy...they made a secret chamber at hogwarts to practice magic cus it was forbidden or something...REAL MAGIC is not like harry potter...
a physical room should be virtualy inaccessable to someone you do not want inside and drown out outside noise. astrial rooms are more complicated and would require your friends to be experienced already in magick.