1995 Ford Taurus power steering pump

Two days ago I was driving my car and I noticed everytime I turned my wheel to go left it would lock up on me and I had to like rip it back to make the wheels go straight I dont know much about cars so I didnt think much of it. When I went to go home I was driving for about 3 minutes and I heard a loud whining noise and my power steering went out completely and there was this constant shreaking noise, so I pulled the car over and turned it off. I popped the hood and I checked my power steering fluid and it was full but it was black, there was not a smell or anything, so I turned my car back on and the shreaking noise was still there but its coming from my belt so I turned my car off agian and ended up getting picked up and left. I have been told I need a new power steering pump but I dont have the money to take it into a shop so I plan on doing it myself, my question is is it my pump or does it need a flush? If it needs a pump how do I do it by myself?