Get & Set Data Between C# Application & Yahoo! Messenger

[Sepehr Adel]

hi to all
I'm a c# programmer
i have a 1 question :
how can i send data to controls of other application windows??
for example : how can i send & received message with C# to this windows ???

please help me
thanks

[Sepehr Adel]

this is Yahoo! Messenger (ChatWindows):


this is Yahoo! Messenger (ChatWindows SendButton):


this is Yahoo! Messenger (ChatWindows SendTextBox):