When someone you followed has started a live.ly broadcasting, you will receive a push notification on your phone.
Besides, you may also find the friends who are doing a live.ly broadcasting in the live.ly app. You just need to open the app and tap on the "flow string" icon in the bottom left corner to enter the channels page. You may also enter that page by just swiping left. Your friend's broadcasting will be shown under the "friend's channels" section (in the upper part of the page) with a flashing flow stream icon.