Have you ever bleached out your hair before? was it a good or bad experience?
You should really not do this yourself if you are not experienced because
1. you could make your hair fall out or really damage it
2. you could blister your scalp
3. you may turn out with orange hair
The list goes on but I don't want to freak you out.
Schwarzkopf BC Bonacure Color Save - True Silver Shampoo
the violet shampoo will help you achieve that whiter blonde look.