2004 Saturn Ion I can't steer

I was driving yesterday when I went to exit onto the highway, I slowed form 70 km to 50 km and found that when I tried to make the exit I could barely steer the vehicle. I had trouble steering all the way home (20 minutes longer). I thought it might be the power steering fluid. But I can not find any place that would hold the steering fluid. This is my first car and don't know much about them. I also just acquired this car and there is no owners manual in it. Where would this be located? And if it does not have one then what else could be the problem? I can steer it but just barely and I really have to yank on it hard just to get it to move. It seem fine until I drive for a little while, then it act up again.