Not sure what camera you're using. This is a problem of metering. The sky is dominating the whole picture and the metering (I'm assuming you're using matrix or evaluative metering) expose the sky properly; which it has done its part as it is designed to do.
To properly expose the football game, you should use center-weighted or spot metering to get the correct exposure and lock your exposure as you focus on the ball game, then shift your camera to compose and snap away. However, this might over-expose your sky and make it very bright (to help a bit, a Neutral density ND will help a bit) but your football game will be OK. OR +EV if you don't have the metering option but should result in similar effect.
Another option (if your option is very limited) is to use Photoshop and brighten the bottom part separately (can use the highlight and shadow adustment in PS CS). This maybe your best option.