Installation of a linux system you will need a flash usb stick or empty free dvd to burn to  disk to write the ISO files to stick or disk . Down load the operating system here your choice MINT LINUX or UBUNTU down load to computer and  then put files on usb or disk what you will find to start off with both come with powerfull desktops.Mint is the better of the two both distros have great office suits  libra office witch is as good as MSFT office also theres a large software center and all software is free on linux tons of science based games utility and just about everything you could think of .
 If your installing on a windows computer go to bios settings change first boot to to what ever your using to boot cd drive or usb stick put either in the computer and restart your computer .It should boot right to linux when it starts and the installer follow the on screen directions for an easy install. Your computer will be much faster and use far less resources running linux you be amazed at the performance of even old tired out dated machines on linux lubuntu is a nice light version thats good for older machines enjoy !