You could take a look at several file management apps. Two that come immediately to my mind are iFiles ($3.99, USD) and Goodreader ($4.99, USD). Both of them are available at the App Store.
With either, you can create folders and then put whatever type of files you wish into the folder. You can also make sub-folders. Both connect to Dropbox (an online storage) to download or upload, can connect to your computer, can send files between devices, use the "Open In..." function to view your file in another app, access the Photo app on your device, allow you to e-mail your files, etc.
Personally, for what I use it for, I use iFiles. However, Goodreader has been called the "Swiss Army Knife" of apps. And, again, there are many more out there.
Good luck in your decision.
Marilyn