Hi SanSingh !
I suggest you to follow Burr's guidelines :) but let me show you an alternative way to put a patch on your object (or something like that)

I try to replicate your profile moving few points




now extrude it



hide the profile curve,select red edges and join them, edges will be sections and rails for sweep



this is resulting surface after sweep



do the same with the back,join all surfaces and you'll obtain a solid



maybe this won't work with your model but in future could be helpful....just an idea ;)

M

Thanks BurrMan, it worked!

Cheers.
Sandeep.

Hello Keith,
thank you for the tip!

Cheers.
Sandeep.

Hello Stefan,
thank you for the file and all the options.

The boolean and difference option worked for me!
Thank you so much!

Cheers.
Sandeep.

Thank you again!

Cheers.
Sandeep.

Hello Mauro,
thank you for going through all that effort to help me out.

BurrMan's suggestion worked. I will also keep your method in mind as an alternative.

Thank you so much! Much appreciated.

Cheers.
Sandeep.