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:
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