How to send text messages on ipad Unicom 3g network card?

Ipad Unicom 3g network card to send SMS operation is:

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.