You can email the documents, yoy can use a cloud management system like DropBox or Apple's iCloud, you can use iOS File Sharing with apps that use file sharing.
it depends on what typ of files that you want to transfer and if you have a compatible app on the iPad that will, open, edit and save that file type. Documents/Files are saved in the apps that can read them or edit them. There is not folder or conventional file storage system in iOS. There are third party apps that will allow you to save different files types in them as well.
For more information about iCloud
iOS: About File Sharing