Welcome to the community!
Sorry to hear you've lost your SIM. You should be able to order a new SIM by contacting customer service. In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
Once you have received your new SIM card, you would likely also need to contact customer service so they may update the information on your account. The online services requires you enter your old SIM card information. Since you have lost your SIM card, the online method would not work.
Hope this helps 😀
Hey @Ting6, you can activate a new sim online, if you still have a record of your old sim number. You can reach out to @FidoSolutions on twitter or Facebook or go to Fido.ca and do an online chat for assistance. I just updated my sim online in my account, I think my old sim number populated in the space automatically and then I entered the new sim number. The update is immediate. One of these methods will surely work for you
you can find the full instructions on how to update the SIM card here.