All of the assets you use in the content of your website are stored in the File Manager. Images, documents, movies - anytime you're linking to something or offering something for download, you're going to use the File Manager to pick that asset. By managing these files for you, concrete5 adds permissions, versions, custom attributes and a whole lot of other powerful tools to the mix. This is NOT a place to manage the PHP files that power your website. 

• Keywords - searches the file name and meta data available for a match.
• Sets - files can be organzied into Sets. Sets are NOT a hierarchy like folders, but rather behave more like Labels where a file can be in more than one Set easily. You do NOT have to manage a folder structure for your files in concrete5. 
• # Per Page - controls how many results to show on a single page. 
• With Selected - click a few of the check boxes next to files, or the check box in the header to select all of them. The With Selected menu will let you perform bulk actions to all of those files. 
• Add File(s) - If you just want to upload a single file quickly, hit browse, pick the file, and then hit Upload File. 
• Upload Multiple - If you have a bunch of assets to upload at once the Upload Multiple interface lets you do that. You can pick many files for a bulk upload, you can first FTP files into an Incoming directory on the server to import, or you can point to remote URLs for concrete5 to pull a copy of the file into the File manager for you.