First of all, just double check that the SIM card is installed correctly. I know it sounds obvious, but a simple thing to check.
How did you get your phone?
If you bought it second hand or refurbished. It could be carrier locked and you would have to either use a SIM card for that network provider or try and get the phone unlocked.
Could also need your SIM card carrier supplier to send you the network settings to the phone.
Try going into settings and then connections. You will see network and SIM card settings in there.
Also possibly if its a duel SIM phone, put the SIM card in the other slot on the SIM card tray.