Hello Tuhin,
Headlines must fit space- one column or two column or more, and the size of the headline further complicates the case and is counted in points, most letters being one, an l or i is 1/2 point and m is two points. The present tense is used in headlines as part of news "style." (see below) Each column has certain number of points it will accommodate in varying font sizes.
I would presume - from past experience - that "Lara smashes century" would be on the Sports page and would refer to a person who scored over or under 100 in some sport. The lingo on sports pages is even more complicated than regular heds! (Heds are news speak for headlines - see how we shorten?)
Now, I have given you a very slight indication what knowledge is required in order to write a headline so I am sorry but to honor your request to Please explain in details to me. would require too much time. I respectfully suggest you avail yourself of books on newspaper writing and editing at your local library, Or. Call your local newspaper and ask for the address or the closest Associated Press (AP) office- the AP publishes a Stylebook - that you can purchase for a reasonable price - that details the requirements of usage in newspaper for writing and for heds. Some papers (i.e. The New York Times) have non-AP stylebooks they have amassed and which are not generally available to the public.
Hope this helps a bit
Hi Jackie