engine problems

Ok, I have a 1997 200sx SE with 141,000 miles. The car leaks oil badly. What happened is I was driving on the freeway (acceleration was slow). As I was driving the car it suddenly slows down and I hear a rattling noise from the engine. After being stopped I try to start it, it starts but I hear a loud rattling noise and I turn it off. I got some oil and put it in, the battery was also dying. Now its in my yard, battery seems dead, and the car doesnt makes noises at all when trying to start, except a once click sometimes. Did my engine seize up? How can that be fixed? Where could oil be leaking from? My front right rim gets dark from all the oil.