First of all you mast download the software from this link: http://www7.buyoffice.microsoft.com/emea2/default.aspx?cache=676426608&WT.mc_id=ODC_ENUS_GenTry_Control&culture=en-GB
After that open the exe file and run it ,Thin put the serial key if you have it, Now click CONTINUE
button , Such as the picture show
Then accept their terms of the agreement , After that click on CONTINUE button like in the picture
Now click on INSTALL NOW to began installing your software
Just wait for a few minutes to setup Microsoft office 2010
finally you are finished just click on CLOSE button , Then open your software and Enjoy