You can either use the shortcut bar or go to settings.
- Swipe your finger from top of the screen to bottom to view the shortcut bar
- Press this icon from the list
Or go to settings => More => Mobile data => Choose network if you have 2 sim cards in your tablet => Turn on data.
NB: One thing is to select Data simcard
- Go to settings
- Dual management/SIM management
- Select Data SIM card. This is the Sim card that you used to buy data.