The tri-cut SIM is perforated so that you can break out a Standard, Micro or Nano SIM from the same card. These can then be re-plugged if you need to use the SIM in a different size. 

Carefully break off the SIM from the plastic holder. Depending on the type of your devices’ SIM slot(s), detach the Standard, Micro or Nano SIM card format. Insert the SIM into your device and switch it on.

The SIM will automatically detect your location and configure the necessary settings required to register to a network operator. Make sure you are selecting a partner provider only. To select a different network operator other than the one registered you can do so by selecting one manually in your network settings of your device. Should you need to access your location settings for troubleshooting purposes please refer to the below steps

In your Apps menu looks for SIM Toolkit or SIM Services and select
Select Multi-Account > Country Selection
The active setting will have the asterisk (*) sign displayed next to it.

Once your SIM has registered to a network operator you will receive a welcome text message and details of how to set up your internet on your device (this is also shown in Step 9 below). This is only applicable when the SIM is first used.