1. Find " SIM settings"
Press All settings.
2. Select option
Select a network manually, go to 2a.
Select a network automatically, go to 2b.
3. 2a - Select a network manually
Your mobile phone searches for networks within range.
Your display will tell you if you have access to the network you've selected.
4. 2b - Select a network automatically
Wait while your mobile phone finds the network.