Upgrade Mac OS X 10.4.11 to newest software

Question

Thanks to Allan Eckert's suggestion,
Dear Friend,
I had been to the Apple shop in Perth and purchased Snow Leopard to be shipped the following week (via on-line purchase).
Since we bought the following machine back in 2007 (or 2006?), 
Mac OS X
10.4.11
Processor 2GHz Intel Core 2 Due
Memory: 1GB667MHz DR2 SDRAM
We have never done any program upgrade,... even we do not read all the emails sent by Apple team.  We are just enjoying the machine so deeply and ignore the need to maintain it properly.
My little concern is:
Will my Mac recognize the DVD I bought (on it's way to me), and the upgrade will automatically be processed?  Or, is there any program/patch I need to go through before it can recognize this DVD?
Or, am I worrying too much now, let's wait and see?
Thank YOU!

Answer 1

Before embarking on a major OS upgrade, it would be wise, advisable and very prudent if you backup your current system to an external connected and Mac formatted Flash drive OR externally connected USB, Thunderbolt or FireWire 800, Mac formatted hard drive. Then, use either OS X Time Machine app to backup your entire system to the external drive OR purchase, install and use a data cloning app, like CarbonCopyCloner or SuperDuper, to make an exact and bootable copy (clone) of your entire Mac's internal hard drive. This step is really needed in case something goes wrong with the install of the new OS or you simply do not like the new OS, you have a very easy way/procedure to return your Mac to its former working state.
Then, determine if your Mac meets ALL minimum system install requirements.
Mac OS X v10.6 Snow Leopard system requirements
Purchased Installer disc here.
http://store.apple.com/us/product/MC573Z/A/mac-os-x-106-snow-leopard
To install Snow Leopard for the first time, you must have a Mac with:
An Intel processor
An internal or external DVD drive, or DVD or CD Sharing
At least 1 GB of RAM (additional RAM is recommended)
A built-in display or a display connected to an Apple-supplied video card supported by your computer
At least 5 GB of disk space available, or 7 GB of disk space if you install the developer tools.
Once you have installed OS X 10.6 Snow Leopard and have updated all the way to OS X 10.6.8, you can decide if you want to upgrade your iMac's OS further.
OS X 10.7 Lion system requirements
Purchased emailed download code here.
http://store.apple.com/us/product/D6106Z/A/os-x-lion
To use OS X 10.7 Lion, make sure your computer has the following:
An Intel Core 2 Duo, Core i3, Core i5, Core i7, or Xeon processor
Mac OS X v10.6.6 or later to install via the Mac App Store (v10.6.8 recommended)
7 GB of available disk space
2 GB of RAM
To install OS X  10.8 Mountain Lion, 10.9 Mavericks (free upgrade, but currently unavailable) or OS X 10.10 Yosemite (currently available free upgrade) you need one of these Macs:
OS X 10.8 Mountain Lion purchased emailed download code here.
http://store.apple.com/us/product/D6377Z/A/os-x-mountain-lion
iMac (Mid-2007 or later)
MacBook (13-inch Aluminum, Late 2008), (13-inch, Early 2009 or later)
MacBook Pro (13-inch, Mid-2009 or later),
MacBook Pro (15-inch or 17-inch, Mid/Late 2007 or later)
MacBook Air (Late 2008 or later)
Mac mini (Early 2009 or later)
Mac Pro (Early 2008 or later)
Xserve (Early 2009)
Your Mac also needs:
OS X Mountain Lion, Lion, or Snow Leopard v10.6.8 already installed
2 GB or more of memory (I strongly advise, at least, 4 GBs of RAM or more)
8 GB or more of available space
Next,
If you run any older Mac software from the earlier PowerPC Macs, then none of this software will work with the newer OS X versions (10.7 and onward). OS X Snow Leopard had a magical and invisible PowerPC emulation application, called Rosetta, that worked seamlessly in the background that still allowed older PowerPC coded software to still operate in a Intel CPU Mac.
The use of Rosetta ended with OS X Snow Leopard as the Rosetta application was licensed to Apple, from a software company called Transitive, which got bought out, I believe, by IBM and Appe  could no longer secure their rights to continue to use Rosetta in later versions of OS X.
So, you would need to check to see if you have software on your Mac that maybe older than, say, 2006 or older.
Also, check for app compatibilty  here.
http://roaringapps.com/
If you have any commercial antivirus installed and/or hard drive cleaning apps installed on your Mac, like MacKeeper, CleanMyMac, TuneUpMyMac, MacCleanse, etc. now would be a good time to completely uninstall these apps by doing a Google search to learn how to properly uninstall these types of apps.
These types of apps will only cause your Mac issues later after the install of the new OS X version and you will have to completely uninstall these types of apps later.
Once you have determined all of this, you should be able to find the latest versions of OS X by clicking on the Mac App Store icon in the OS X Dock and then login to the Mac App Store using your Apple ID and password and if you purchased a download code, input that code.
You can then begin the download and installation process of installing the newer versions of OS X from the Mac App Store.
Good Luck!