how can we display a panel or small image in the desktop screen before starting our application
and after some time it should display the window pertaining to it

solution is welcomed in any lnaguage
c/c++/java

Just create a window with no border or title bar buttons and have it display in the center of the screen. I guess the easiest option would be to have the user dismiss it by clicking anywhere on it.

No, I won't do it for you.

I guess you could show a dialog with the required graphics in it's backgound at startup, on the WM_INITDIALOG event, or WM_CREATE event; set a timer at that moment, and when the timer throws the WM_TIMER event after the required time-interval, you can close the Splash Screen.

google for "splash screens". Here is how to do it for MFC program.