i searched a lot ol across web , could'nt get a solution to my problm ... viewed many articles but only found manual apps or s/w's to record a selected area of my desktop ..... can anyone guide me telling hw can i do it programatically in my form on button click events .... there must be respective start stop events .... please help me

You won't be able to do this entirely in C# unless you utilise something like SharpDX.

You will need to call out to a C++ library in all liklihood.

Once you have the stream, you can display it on a form. A picture box might not be the best control for this, but it totally depends on how the video data is streamed to you (for example, you might have a WMV stream rather than an array of bitmaps etc)

can u suggest me some links .. how cn i use c++ in my visual c# app ,, as i have entire application in visual c# .. and after that what to work on to get the selected area of screen captured ??

I would scour google for a C++ library that can capture a desktop area.

You will be able to link to your C++ from C# by using DllImport. This allows you to specify the method signature and library that you're calling. The .NET library will handle the specifics.

I'm afraid I don't have any links to give you, only a general idea of how it would work. But unfortunately I don't have the time to do any discovery programming for you.