You will get a basic crown based on your level. You can also purchase special crown from the 'Item store' from 'My page'. The crown will show on your mini profile as well as next to your message during the broadcasting.
You can level up by earning EXP and here's how you can get them:
1. Send gifts
2. Receive gifts
3. Buy items
4. Broadcasting as a host or a guest
5. Get followers
6. Join live room