help please for an exam

I want to write a program to display

Code:

 			 				       Function name

marks- textbox    update status<----  button
			 

and if marks<35 update F
Marks= 35 update S
Marks<=50 update C
Marks <=75 update B
marks< 75 update A







plz help me how do do this.. plz I this is urgent!!!