I AM HAVING SOME DIFFICULTIES IN INSTALLING SOME SOFTWARE LIKE PDF READER CAN SOME ONE HELP
PDF reading and printing comes built in with most Linux distributions including Ubuntu. I am not sure which version that you are using. There are many PDF readers that you can install from the repositories.
Launch the Software Center or Synaptic and Search for PDF Reader and you will find several. The most common is Evince which shows in the Menu under graphics as Document Viewer. The best is Okular which is part of KDE and will need to be installed. Okular reads just about any document format such as most e-reader formats.
I would bet that you already have Evince installed. Double click on a PDF from a file manager such as Nautilus and it should open in Document Viewer.
BTW, do NOT type in all caps if you expect help. It annoys most people as it is like yelling what you are typing.