If you ordered the phone online, and have a Koodo account with a previous phone, you can just switch the SIM from the old phone to the new. If they are a different size, contact Koodo to get the SIM updated on your account so you can use the new SIM in your new phone.
If this is your first phone and account from Koodo, you should receive an email describing how to register your SIM by following a link in the email. The email will also include your phone number. Check your junk / Spam folder for this email, but if it has not arrived, you should wait a day or so, as Koodo has been overwhelmed with orders recently, and my be a bit behind in sending activation emails. If you still have not received the info, reach out to Koodo, and they will address it for you.