Hi,
True, you need to use "File System Task".
After adding the File System Task to your control data , choose edit.
steps :
1) Change operation to : Renaming file.
2) Select your file to be rename from : SourceConnection.
3) Type a new file name in the : DestinationConnection.
4) You can choose to overwrite/not overwrite in :OverwriteDestination.
Execute the task.
This is the simple and faster why.