By default, broadcast messages will be sent to all of your active subscribers. However, you can send a broadcast to only part of your list (which we refer to as a segment):
How to Send a Broadcast to a Segment
You'll first need to create the segment that you want to get this particular broadcast.
See how to create a segment. Then, send a broadcast a message to that segment.
Under the "Who should receive this message?" section, click "Edit" to select the segment of subscribers you would like to receive the message. Here, you can also include/exclude other lists.
When you're satisfied, click "Apply".
After you have edited your message and set your segment, you can schedule your broadcast as intended.