Generally the internet will work automatically when you insert a new SIM, but you may need to configure a special “APN” profile to use while you’re abroad.
The APN defines the network path for all mobile internet connectivity.
Each wireless mobile provider has a unique APN that should be programmed into your phone before you can connect.
If you have an iPhone/iPad – make sure you double check your instructions, you may have to download a new APN profile BEFORE your departure.