When viewing a concern click on  Send Alert To... on the right-hand side underneath Actions



This will pop up a box allowing you to select the colleague you would like to alert and send them a message: 



Selecting the staff members field will allow you to select either user groups, or by clicking the + next to a user group, individual staff members within a user group:



If required you can then write a message to inform the users why they are receiving this alert. This message will be displayed in the email that is sent to them.