Setting selected databases in the backup database task from a variable

Hi

I am using SQL Server 2014

I wanting to create a SSIS package, using the backup database task to backup specific databases.  I have a script task which writes the list of databases to variable object, then thought I would loop through the object and fire the backup database task for each database in the list.

I thought that you could pass in the database name in via an expression, but I can't see selected databases in the property dropdown.  Is it called something else? or another property which I use that I pass in the database name I want to backup

Ideally I want to backup each database individually, because I have another script task which I want to run in-between each backup

Thanks