The Thread tab is located under the Wireless perspective in grid view. This page will list all of the current thread devices on the site along with their current information. To add a new thread device simply select the control system from the last row in the view which you want to add the thread device to. If the control system does not appear in the list then it may not support thread devices. Selecting a control system will bring up a dialog to enter the QR code for the thread device.
Once a valid QR code is entered then clicking the create button will create the thread row and it should begin the adoption process. You will see it appear in the list not long after creation. The right click menu allows you to readopt or clear commissioning credentials if there are credentials present for the row or you can remove a thread row.