First, make sure that the SIM card is well inserted in the SIM card slot of your device (please refer to the instruction manual of your device).
Then, the only thing you have to do is to connect your device to the Ubigi network and create your personal account. To do that, please follow the instructions here.
Voilà ! You can now enjoy your Ubigi services.
Note: in case there is no SIM card inserted in your device, first make sure it is compatible with Ubigi service: Which WINDOWS 10 devices are compatible with Ubigi services?
If it is compatible and you never had a SIM card or you lost it, please contact device manufacturer directly to request a new one.