How can I send to different Groups using Broadcast?

You can create different groups by clicking on Settings >> Groups >> New groups Click here.
These groups can be used in Broadcasts to send messages. You can select multiple groups to send messages. 

Remember : The groups based on Days of the week are automatically created by GeniusOne® when students are assigned a Timeslot. These are displayed in the Broadcast and can be selected to send Broadcast only to those students coming on that particular day.