How To Install Photoshop Lightroom 4

First of all you mast download Photoshop Lightroom 4 from this link :  
https://www.adobe.com/cfusion/tdrc/index.cfm?product=photoshop_lightroom

Then open the setup file and run it ,Click NEXT button to began installing

Just wait a few minutes then click NEXT button

OK now if you have the serial key put it , If you don't click on I want to try 
Then click on NEXT  button

Put the serial in the field  ,As shown in picture

Just wait  a few minutes to complete installing

You are done click on FINISH button , Like in picture

Now click OK such As picture shown

Just  wait a few minutes to run Photoshop installer

OK now click NEXT to began install Shield wizard for adobe Photoshop Lightroom 

Then accept their terms agreement , After that click NEXT

After that click on next button

Now Click INSTALL button to began installing shield wizard

Now click FINISH button, You are done ,Setup is Completed , Enjoy