I am a noob I admit it, that why I am trying to gain knowledge from you the experts. I don't know that you cant loose fat and gain muscle at the same time. So kindly suggest which should I tackle first and advise accordingly.
The reason is pretty simple:
To gain muscle you need to eat in a caloric surplus (ie. eat more calories than you burn).
To lose fat you need to eat in a caloric deficit (ie. eat less calories than you burn).
See the problem? They are contrasting goals.
As a n00b however you might experience what are known as n00b gains, basically because if you have never done much exercise before then once you start your metabolism will skyrocket meaning you could lose fat and add muscle simultaneously, but this won't last long!
As for which to tackle first, it's up to you really. If you are overweight and are carrying what you perceive to be an unacceptable level of body fat, then cut first. But otherwise I'd recommend bulking first and cutting later, because when bulking you will add a lot of muscle (if you do it right) and generally this will boost your metabolism quite a lot, meaning the more muscle you have the easier it will be to shed the fat once you come to cutting time.
Plus you will start to look a lot better when you start adding muscle, even though you aren't necessarily shredded, but the point is if you just decide to cut down first and get to a level of body fat where you can see a six pack, you will probably not be happy with how you look because you won't have much muscle, and you will just look skinny!
So it's up to you, but bulking first seems to be the sensible thing to do (to my mind at any rate).
Whatever you decide to do, you should check out Mark Rippetoe's Starting Strength routine, it's generally renowned as being a fantastic beginner's routine that will have you piling on muscle mass in no time.
Good luck!