Tennis as a subject is like an ocean - there are so many things to learn, practice, perfect and implement that it is simply not within the scope of an article to explain all of these.
But if you are absolute newbie to the game, let me assure you one thing that this is one of the most exciting sports to pick up, one of the most challenging games to play and one that will give you a lot of satisfaction.
  So where do you actually begin? The most important things to start with are the tools - you need to ensure that you choose the right racquet.
There are other things like shoe, clothing,etc.
but do not worry about those as they are really not necessary for you to start hitting the ball.
  Once you select the right racquet - one with a head large enough so that you can hit easily enough, the next step is to start hitting.
If you can afford a coach, it should be great.
If not, look out for video as well as textual advice that is available on the internet.
You need not go through the intricacies at this stage.
  Once you have learned to start hitting the ball in the middle of the racquet, you need to start learning to play a long shot rally.
Have another friend to play against you simply to train you to play a shot.
Even playing against a wall should be good.
Once you master this, start serving and start playing against others.