What I understand is that you want to copy Sheet1 column A, when Sheet1 column C is "OK", to Sheet2 column C.
What I don't understand is what the button on Sheet3 is supposed to do?
This line also confuses me:
"copy it in C1 of sheet 2 and select the 7th row as o/p".
C1 of Sheet2 is the output, what about the 7th row?
Won't the 7th row be affected when column C gets filled with data?
Do you mean the entire 7th row, or just a few columns of the 7th row?
Consider posting some screenshots (always be careful with sensitive data) to help clarify.