Once you have a Premium subscription it's very easy to make group video calls. You can simply click on the + button on the toolbar at the bottom of the Skype window and then click Add People to This Call. Or, better yet, you can select all particpants from your Contacts List and then click Video Call, calling all particpants at once.
One key to successful calls is to make sure everyone who will be on the call is running the
lastest version of Skype. Don't accept "I have the latest." Get everyone to click on Help > About Skype and see if the actually have the latest version, 188.8.131.52 as of today.
Please note: I do not respond to requests for help via Private Message.