Welcome to the community!
If you would like to bring your phone number from your previous provider, you would need to contact customer service so they may request the port-over from the other provider. 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 Fido requests to port your number to their services, you should receive a text message to which you must respond in order for the porting to proceed. It is important that you do not cancel your services with your previous provider prior to the porting process being completed (see here).
Hope this helps 😀