Buy the ticket online
On the B-ticket website you can book the time and date of your visit. You will receive a confirmation email, do not throw it away.
Bring the receipt to the ticket office
Print out the confirmation email and bring it to the ticket office, where it will be exchanged for an entrance ticket.
Skip the line to enter the museum
With your ticket you can now enter the museum skipping the line through the fast track lane. Check the map of each museum to find out where it is.