How to send text messages with Ipad 3G Unicom card?

The operation of sending SMS with Ipad 3G Unicom card is as follows:

Step 1: Click the "Settings" icon on the desktop.

Step 2: Open "imessage":

Step 3: Enter your Apple account and click the "Login" option.

Step 4: After system verification, it shows that iMessage has been activated and turned on:

Step 5: Click the "imessage" icon on the desktop.

Step 6: Click on the blue plus sign icon in the upper right corner to open the address book on the iPad and select the contact we want to send iMesaage to:

Step 7: Enter the information content and click Send.