First, open the applicatin Line and select your friend's contact that you want to make a call with or searching the contact name by tap search on the top of the screen, type your friend's name, tap search and you'll see your friend's contact. Next, select the contact, you'll see the detail of your friend's contact. Finally, tap "call free" if you want to make an audio call ,but tap "video call" if you want to make a video call.