how to send string message to another app and click button

I have one One application exe which is used for run all exes from a perticular folder. for that We have to give  the path and click the button.Now i have to make new application in vb.net or c# to  check if any new files is there in specific folder and if there it automatically takes the path and send it to that application and automatically press the button.I also use spy++ but i did not get the exact result  and i dont have the code of that another exe.Please help for that

 

Thanks