Good day to you!
There are no difficulties in installing CentOS, please find below my complete pictorial instruction.
Choosing CentOS distro
There are several types of CentOS distros, they differ in size and set of the programs included:
- Minimal – only the programs that are necessary for functioning of the operating system, nothing extra;
- NetInstall – from this distro you can install any version; however, Internet connection is required during the installation;
- DVD – a standard distro, includes all the necessary programs in the programmers’ view;
- Everything – the most complete distro, which includes every possible program;
In case you install CentOS for home use or just to “touch” it a bit, I recommend using DVD or Everything. If you are making a server, Minimal will be the best option. By the way, if you require a developer’s server or a server for a small web site, the easiest way is to use a cloud service DigitalOcean, there you can unfold CentOS image and get an operating server in 2-3 minutes without installing anything. Just follow this link, and you will receive 10$ on your account without any additional conditions (an affordable server with CentOS costs 5$ per month).
Preparation for installing CentOS
So, you have chosen a distro, now proceed to to the official web site of CentOS and download it. You can use torrents to speed up the process; the torrent files are located next to common ISO. If you want to install CentOS on a virtual machine, ISO image will be just enough. If the installation will take place on an ordinary PC, you will require a bootable flash-drive as well. How to recorder an image on a flash-drive and make it bootable, you can read in or special article: How to create a bootable USB flash drive (an instruction).
Installing CentOS
1. Use the pre-made flash-drive or create a new virtual machine form ISO image; you will find yourself in the installer menu:

There is no need to set any additional parameters, therefore, just click Enter button.
2. The installer will check the distro, after which a nice-looking graphical interface will be uploaded:

Choose a language and click “Continue”.
3. From the next screen you can select regional settings, the type of installation (don’t miss this point, otherwise, minimum configuration will be installed) and other settings; after that press “Begin installation” button.
4. Make sure to define the root user password:

The installation has already begun and is in progress even when you are setting the root password, wait until it is over.
5. Before long, the installation will be complete and the installer will offer you to reload your computer.
After reloading, you will be able to enter the installed CentOS as root user, using the pre-defined password:

If you have any questions or need more details – please, ask a question or leave a comment.
Good luck to you!