Alternately, if you could add/move a fan at/to the top of your case, pointing the CPU cooler fan up towards that fan would help improve air-flow by taking advantage of convection. For your current setup though, you would want to do as Gamer said.
The most important thing when deciding fan setup is figuring out which direction fans blow. I'm never able to tell with my hand alone, I have to take a light material and hold it close to the fan and see which may it moves (like a piece of paper or string). You might be better at gauging this than me though
Which way does your case and CPU fan blow?