Well - All the Canadian devices use the same Firmware - So it wouldn't really matter if you Flashed Bell - Rogers or Telus for example AND the latest versions are all the same.. So if you downloaded the Bell or Rogers Firmware it doesn't make any difference - Especially since I don't know what Carrier's Software Version is installed on your device?
Have you contacted your Carrier in Tunisia & asked them about the One UI update?
To install the Firmware with Odin - You need to Download the Firmware to your computer - Extract it & you'll have 5 Md5 tar files:
BL
AP
CP
CSC
HOME_CSC
You copy the respective files to the correct slots in Odin - I'm pretty sure since I don't see any Firmware for your Country - That you should select CSC & NOT HOME_CSC for the CSC slot...
In the options in Odin - You should ONLY have Reset-Time & Auto Reboot selected - DO NOT SELECT REPARTITION!!
Boot into Download Mode - Connect your phone to the computer & Wait for the Blue box showing that you are connected & click on Start..
There's plenty of YouTube videos on how to Flash Samsung Firmware with Odin - You SHOULD watch a couple several times BEFORE you start 🐧