From the left panel menu, select the Settings tab near the bottom:

Next, under the SETTINGS in-panel menu, select Carriers:

To add a carrier, click Add Carrier: 

From the EIZ Select Carrier menu, select Sendle:

Finally, to link your current Sendle account, enter your credentials including: Account, API Key (generated on your Sendle portal), and click Next. It is as easy as that! If you get stuck, contact support@eiz.com.au to assist you through the process.