Q: understanding i cloud

a) the "correct" way to access the saved files is through your devices (see (b)). It's integrated in OS X and iOS. The iCloud.com is just a way to access your iCloud files if you don't have a nearby Mac or iOS Device.

b) everything is bundled. in fact all the info on one device will be exactly the same as what is on the other devices.

c) You can use the iCloud Drive to backup any file you want, to get it synced through all your Apple Products.

d) from many apps: for ex:

• the Calendar app will give you the Calendar data
• the Notes app will have your iCloud notes.
• the iWork apps will have your Pages/Keynote/Numbers documents
• safari will have your synced browsing history etc.

The best starting point for iCloud is this page:  http://help.apple.com/icloud/#mmd0558ce3

To answer your questions we would need to know how you want to use iCloud.  There are so many different ways to use it.

• The basic setup would be to have iCloud sync all your Contacts, Calendar items, Notes, Remainders, bookmarks, iCloud Mail. You enable this by setting up the Internet Accounts and iCloud Preferences in the System Preferences on your Mac. (              Set up iCloud       )
• If you want to sync documents as well, you enable iCloud Drive in the System preferences > iCloud.  (http://help.apple.com/icloud/#/mmd0b4a7f5e8). For iWork documents see: iCloud: About using iWork for iOS and iCloud
• If you want to use iCloud for your Photos, you either use the Photo Streams (iCloud: Get help using My Photo Stream, iCloud: iCloud Photo Sharing FAQ)  or iCloud Photo Library (Beta). (iCloud Photo Library beta FAQ).  iCloud Photo Library Beta is not yet supported on Macs, only on mobile devices with iOS8. If you enable it, it will disable the Photo Stream from the Mac to the mobile devices.

a)I believe that the correct way/Only way  to access the  saved info is through iCloud .com ?

 

No, you can access most info on iCloud.com, but if an application supports iCloud like the iWork apps or Pixelmator, for example, all devices should be able to access the documents directly. And iCloud Drive will just look like an external drive on all your Macs, so you can see the docments like on any external drive.

b) is the saved information all bundled together ,or is it possible to access each devices'  content individually?

iCloud is a common storage for all device. It is not separated by device. If you update a document on one device, the changes will be synced to all devices. (iCloud Drive FAQ)

c) from what i understand ,it is only possible  for iCloud to store MAC software created documents etc..  (e.g. pages /numbers) ? if this is the case

You can store any kind of document on iCloud Drive, not just native Mac applications. The documents will be stored in iCloud, and synced to other Macs. But to open the documents on your iPhone or iPad, you need an iCloud compatible application on the mobile device, that can open the document. For example, I store all LateX documents in iCloud. I can use them on all Macs, but not on my iPhone, for want of LaTeX on the iPhone. But don't store packages in iCloud, only documents or compressed folders.  Don't move your iPhoto Libraries to iCloud Drive. The updating will break the references inside the database entries and corrupt the library.

How can i back up  my other documents.

iCloud is not meant for backing up Mac documents at all, neither native Apple apps nor third party apps. It is meant to store them and sync them.  Any edit you do will be updated immediately across all devices. If you accidentally delete a document, it will be gone from all devices and you cannot restore it.  Use Time Machine to backup your Macs.

iCloud does only backup your mobile devices: See:  iCloud: Backup and restore overview

d) where how  do i access the cloud from my i phone ?

By opening an application that can access iCloud for each type of document you store in iCloud. You enable the iCloud ready apps in the Settings > iCloud.

I have documents  and other stuff which i want  to share between devices   using  i cloud ,

They are mainly stored  in my documents folders, in the  'documents section'  FINDER.

Are your other devices mobile devices with iOS 8 or other macs?

To share the documents with mobile devices, copy them to the predefined application folders on iCloud drive - Keynote documents to the "Keynote" folder, TextEdit documents to the "TextEdit" folder on iCloud Drive, etc.

You can copy any document type to iCloud Drive, and move the documents into custom folders you create on your own, if you simply want to share the documents between Macs.