how to change the text of a field in cdr file using c#

Hi i am yogesh i just joined this community. i am a developer.. i dont know much about coraldraw...

i need to manipulate the  text  of a field in cdr file(For example:- from 'yogesh' to 'sharma') using c# code....

i know it is something like...

CorelDRAW.Application cdr =
                    new Application();

                cdr.OpenDocument(@"C:\Users\user\Desktop\500074.cdr", 1);
this will open the cdr file but how should i manipulate text of its fields...

Please give it with example...if anybody knows..Any help will be highly appreciated....