Hi Vibha - Thank you for providing several complete examples as shown on the page you cited.
If I am correct, in order for new pictures to look the same as the ones on the "team" page, what you really want is for two things to happen:
a) The size of the person (or the person's head) in pixels should be adjusted to be approximately the same in all pictures (as I suspected); and,
b) After (a) is done, when necessary, white space or some neutral background should be added to the result of (a) to bring the overall pixel dimensions up to that of the wide rectangles on that page.
I am describing this in the simplest and clearest way I can. If it's not clear to you, may I suggest that you bring my description to someone who speaks your language and is used to working with digital images.
Another possibility is for one of our other members to show you by example what I am talking about. Unfortunately, I am in the process of performing maintenance work on my computer, so I can't illustrate what I am talking about myself.
Good luck with this task!
Tom M