If you did not receive the confirmation mail please check if you've written your email address correctly by going into your profile section. If not, please correct it and press 'save'.
If your email address is written correctly, check your spam folder in your mailbox. Sometimes it lands in there!
If both of the above weren't the issue, try to book a mission from the map. A 'send confirmation email' notification will appear. If you click it, another confirmation email will be sent to your email address.