Transmission leaking fluid

The car would start but when I put it in reverse or any other gear it doesn't go into gear. I press the gas and it just revs up. I put transmission fluid in it and it worked like it supposed to. I drove it a little further and it started going out of gear again. I pulled over and noticed what looked like transmission fluid leaking out from closer to the driver side of the engine. I tried putting more transmission fluid in and it didn't make it go into gear that time. The only lights on are low coolant light and the brake pads are pretty worn down and we been driving it with it grinding. There are like 100,000 miles on it. Oh yeah, the transmission dip stick is missing. I added some pictures where is the car is leaking the transmission fluid. I hope to get a better understanding what exactly is leaking how much am I looking at to get it fixed. Is it possible that it could be something different than a seal that is leaking? I'm not a mechanic so when I look at it I have no clue what I'm looking at. I am trying to get as clear as possible picture I could of the leak.