1993 Toyota Camry transmission fluid came out of transmissi

Hello,
I have just put a used transmission in my toyota camry and about 2 weeks after I installed it I was driving it and the car stopped pulling. Before it stopped pulling I noticed that I felt ginding in the shift knob inside the car. Aftedr I pulled over to side of road I look under car and I saw transmissio n fluid all over the road leading up to where I stopped and a puddle where I stopped. I checked fluid level and none showed up on the stick. When I poured fluid into the car ir ran out on the ground at a fast pace. I kept car running and in gear with brake on and I poured fluid into car and I could hear the gears trying to engage but the fluid was running out on the ground to fast.
what I wanted to know is what is the problem with the transmission and how could I fix it or can it be fixed? And if I had to take it somewhere to be fixed what would it cost to fix? Could I buy the part to fix transmission or do I need another transmission. I need the cheapest way out. Thank you