The File Selector tool allows you to navigate through the file system to select files or folders.
In order to make your way to your file(s)/folder(s), you can either chose to define your folder using the manual input field and click Jump
Or/And you can navigate using the file browser box.
To select a folder, you have two ways:
select the folder and click SELECT
enter the folder and click SELECT
To move up the tree (go to the parent folder), select ..
You can sometimes narrow down the list of files/folders displayed by using the filter option.
If you want to check all the features offered by the fileselector tool, go to the Fileselector hands-on tutorial