How can I connect to the internet by sim card?
The first thing you should do is make sure that your model iPad supports the cellular network you're trying to connect to.

In America, we have two major cellular networks, GSM and CDMA. I suspect that this is the heart of your issue.

Apple's support website has a webpage that helps identify your model so you can continue troubleshooting.

If push comes to shove, you'll need to either call your cell provider or go into one of their stores to have them resolve the issue by either giving you a new SIM or reactivating the device on their network.