To guide the cow to the exit you need to place all the arrow tiles on the correct place. Think carefully first because you have a limited supply of tiles only. Once you think all the arrows are on the correct spots you can press on the RUN button to see if the cow can make it to the exit. I really like to play this kind of flash games.
Use the mouse to select a arrow tile. Once selected you can drop it on any tile inside the level by pressing on the mouse button again.