Hi Richard 
First thanks for your great question.
Here are the steps:
Call the first participant.
Once the call is connected, touch , and then dial the second participant's number. The first participant will be placed on hold.
When the second call is connected, touch to start a conference call.
Repeat steps 2 and 3 to add more people to the conference.
During a call, touch to view the list of participants. You can:
Touch next to a contact to remove the contact from the call.
Touch next to a contact to remove the contact from the conference call and keep them in a separate call.
Touch to return to the main call screen.
It's been a pleasure to assist you today If you have any questions, ask and it's will be a pleasure to assist you :).
Don't forget to mark my answer as the best if u want Have a nice day 
