Hi i want to register my mackbook air but im not

First, yes, you do need an internet connection to not only register it, but to do anything at all on the internet.

Second, if the warranty has expired, there is no need to register it. Apple will recognize the serial number in their system if you need a repair.

And, third, if you buy a device either from Apple or an authorized reseller, your device will be registered automatically nowadays - there is no longer an option to add it manually.

If you want to register it you basically can’t without WiFi. Try going to a local bar or diner that has free WiFi and preferably use a vpn but that’s my suggestion, then register there.

-Lava