Step 1: If your contact is available, double click their name to start messaging with them.
Step 2: Once you've started messaging them, you can add more people by clicking on the Add People contact in the upper right hand corner.
Step 3: Then, an IM window will appear on the screen where you can select which contacts you want in the message.
Step 4: If you want to switch to video call, simply go to the Video Call icon and press Start My Video. To add more people click the Add People icon in the upper right hand corner.