Step 1: Lay of the Land
List of Distros:
Ubuntu - Recommended for beginners!
Debian - Nice all around distro.(looks a bit like OSX)
Kali - Hacker distro for advanced users.
Mint - Like Debian(but with improvements)
And many, many more(full list here)
Step 2: Install
1. Shut down the computer that you wish to install Linux on.
2. Insert CD/USB
3. While the PC boots press either F8, F11, F12, F2, or Delete to enter your boot selection menu.
4. Choose the CD/USB drive in the menu(every computer is different so "shop around" until you find one that boots something other than windows)
5. Now is the time to either test out the distro or install it, chose the install dialog to install or choose the "Live" dialog to boot a live version of your distro of choice.
6. The installation at this point is different for every distro.
Step 3: Your First Linux Steps
Now there are a few things to know before you start screwing things up(you can do this very easily if you don't pay attention).
1. Learn about APT
APT or Yum is your software installer/repo access. Here is an example to show you how to use it(This example installs Google Chrome)
open up a terminal window and type:
sudo apt-get install chromium
most programs are available, and most names work, for ones that aren't working look up: apt-get install "name of your program here" in your browser.
2. Microsoft stuff works! (With WINE)
WINE stands for "wine is not an emulator". Wine allows you to run some windows .exe's on Linux.
3. Where is Word, Excel, Powerpoint, Or Access!
well, the hard and simple truth is...there is none. But have no fear, there are replacement programs that play well with Microsoft Office file types, just type this in a terminal window:
sudo apt-get install libreoffice
4. Have no fear... STEAM is here
For all of you gamers! Steam is now on Linux!
To see how to install visit the Valve Website HERE
5. The community is there for you!
There is a great Linux community on the internet, most likely your distro has a forum website where you can ask questions and get support...or just ask me :)