I used to have some idea about how to install, upgrade, downgrade WINDOWS OS. I wanted to do this like the one I thought of (windows procedure), But I couldn’t follow that procedure. UBUNTU is completely different from windows . It contains installation setup with home wizard i.e; which means, we can have simple UBUNTU home wizard without installing OS. It is very easy to install ubuntu with formatting every thing including previous OS, files etc. I found difficulty when installing UBUNTU in free disk space (Dual Booting) after mounting a path it start installing and stops at 80% and gives an error message displaying “MISSING FILE GRUB package″(I don’t know exactly) on other day my friend decided to format everything in his laptop( this task is done in my friends laptop).I think this is the good opportunity to install UBUNTU. Now, I formatted everything and while installing error message disappeared and ubuntu installed successfully. This is a simple and clear explanation of installing UBUNTU . Remaining steps are really simple like allowing permissions while installing app from playstore eg: selecting language, selecting time zone etc..