Get the OS here: Ubuntu Download Page
After installation there are some things that need to be done.
(The information I am giving here is for the reference of people who are absolutely new to Ubuntu or any Linux for that matter.)
Here is the checklist of the most common things that you need to accomplish in order to make Ubuntu usable for a desktop user:
1) Updating to the latest versions of programs installed.
2) Read/Write support for all drives mounted.
3) Getting the display right.
4) Playing all known media formats.
5) Installing Flash Player for the Web Browser (tricky in case of 64-bit).
1) Updating to the latest versions of programs installed.
Obviously for this you must be connected to the web. After installing Ubuntu you should be seeing an orange icon on the top right corner of the screen. Click it, and Apply the updates. This may take a while.
Alternatively, you may go to System>Administration>Synaptic Package Manager.
Now, click Reload. This reloads your software database to match the latest.
Now, click Mark All Updates, and then Apply.
This process will take about 2 hours on a 256kbps internet connection.
2) Read/Write support for all drives mounted.
If you only had FAT32 file-system, then there should be no problems at all. But if you have NTFS, then you must install a driver for Linux that supports writing on NTFS partitions, since Linux does not have that support in the kernel, out-of-the-box.
For this you must bring up the Terminal from: Applications>Accessories>Terminal
Now type the following command:
sudo apt-get install ntfs-config
This installs the NTFS driver with a GUI to control writing rights on NTFS partitions. You will have to enter your password for the process.
Now, go to Applications>System Tools>NTFS Config
Check both check-boxes and click re-mount. You're done!
3) Getting the display right.
If you have NVidia or ATI based graphic cards then this process is necessary. You must get a script called "envy" from HERE. Get the all-deb package and double click to install.
Now, Applications>System Tools>Envy
Select NVidia or ATI's installation and apply. after doing it, it will prompt for reboot. You should reboot then. Your display is now set!
4) Playing all known media formats.
This is very simple. Open any AVI/MP3/3GP/MPG/etc file and it will prompt you for installation. Select all the packages it lists and click Apply. DONE!
5) Installing Flash Player for the Web Browser (tricky in case of 64-bit).
If you have a 32-bit Ubuntu, this is very simple. Just download the plug-in from Adobe's site and follow the instructions given. If not then:
(for 64-bit only)
Get this file: nspluginwrapper-install-0-1.6.tar.gz
1. Download the script.
2. Right click on the tar.gz and select "Extract Here"
3. Close all browsers.
4. Inside the folder that extracts is a "GetFlash" file, double click on it.
5. Select "Run in Terminal"
6. When the terminal closes, restart your browser.
7. Your done.
Now, get this file: ia32-alsa-oss_1.0.10-1_amd64.deb
Double-click and install.
These are the most basic things that I have covered. Please check this page for more tricks for newbies in future.
Thanks for reading!