i think you have to give him some thing he will like
f
Just ask her for one
ask politely
you ask them
Ask her out and show her that you are interested in her.
Ask your mother.
Give him some reason to want to let you do it.
all you have to do is ask your brother if it would be ok to ask out his best friend.
simple answer ask them
be nice to them and persuade them, ask them.
if its close to your birthday than ask them for it on your birthday.
Ask her - she can only say yes or no.