On the web at Behance.net:

Each time a Behance user reacts or comments on your Work in Progress, you will receive anotification. You will be able to see feedback and reactions made to the corresponding Work in Progress by clicking on the bell icon on the top right of your screen.  

Additionally, you can see who viewed your Work in Progress by 

For a wider overview of the reactions, see the FAQ here. 

Using the Behance iOS app:

Each time a user reacts to or comments on your Work in Progress, you will receive a notification.

If you are using the Behance iOS app with push notifications enabled, you will receive a push notification on your lock screen each time a user reacts on your Work in Progress. You will also see the bell icon, on the top right corner of the app, receive a notification badge.

If someone comments on your Work in Progress, you will also receive a push notification for this action. The bell icon on the top right corner of the app with receive a notification badge. Your conversation with this user will be visible by tapping on the bell icon, then on the Inbox tab.