How to Create an ISO Image from my operating system

I don't know what you mean by "file-system image" or "real data".

Images are of complete partitions. No more, no less.

"Back-up" is a loose term. It might mean anything, depending on the speaker and the context. When you see the term used, the first thing you should ask yourself is "what does he mean by 'backup'? Backup of what"??? Backup of C? Backup of spaghetti sauce recipes?

A "backup" of the C partition or "Windows" most likely refers to an image of the C partition, but you never know what the speaker means.

I mean the disk-image is like a clone; it copies everything in the disk or partitions even the unused spaces of the disk or partition while the file-system image is only the copy of the system file without the unused spaces …
It is true back can mean different things,
In my PC, I have HDD 500GB, that I partition to 3 partitions; C;(250GB) for the windows installing and drivers and application programmes .E,(150GB) for my data and stored things, F;(50GB) intending to be for recovery partition , so in this case is it practical to have my recovery partition in the same physical hard-disk, or it will be useless if my hard-disk fails suddenly

What do you mean by "file-system image"? Images are replicas of partitions, not file-systems.

What do you mean by "system file"?

With your 3 partition setup, I would image C and F, but not E. Data is best backed up by direct file-by-file methods, rather than through an image. Why? Because data is too important to be left to something as shaky as images and image restoration.