At the package level create a package-level variable, set it to data type = String

Create a connection manager for the file (only really needed for the initial set up, as the variable will handle the name of the file when the package is executed)

In General Properties of the control:

> Add a ForEach Loop Control

> Specify the Foreach File Enumerator

Under the Enumerator Configuration properties:

> Specify the folder to monitor

> Specify a file, file type, extensions, etc (wild cards work - i.e. MyFile*.txt)

> Set the file name to "Fully qualified"

Under Variable Mappings:

> Assign the package-level variable you created, setting the index to 0

Add an Execute Script task, add:

EXEC msdb.dbo.sp_start_job N'MySQLAgentJobToExecuteWhenFilesPresent'

Add this package to a SQL Agent job that executes the package.