I have a 1999 Saturn SL1 -- I was leaving to.

I have a 1999 Saturn SL1 -- I was leaving to drive home and at first my car made a thud noise as I reversed, then stopped. I continued to drive to approach freeway, when my car just made another clunk noise and stopped. It wouldn't go forward or reverse to move off ramp entry. Being by myself, a man came to help and got it to go forward moving it off road. Upon viewing under car he didn't see anything, but in checking what he could see (at night, no lights) he put transmission fluid in - said it was low; & put oil in - I keep in my trunk. He got it to move forward, but it still will not go in reverse. I was able (and am able) to drive forward, but when I try going in reverse - it makes a clunky noise & stops right away. I am by myself, and have no money and am trying to figure this out - as I'm new to the area, don't know anyone and don't funds. My car is my only means of transportation to my shop - and have at this time no salary but need to work so I can get enough revenue to have one. A guy by my shop is willing to work on my car, but doesn't know exactly what's causing the problem. I've been researching online, but no clear help unless you pay. I have read about "reverse slam" "change/check transmission fuses, esp. TLPS; also using Trans X and running in reverse; also replacing the shaft nut. Just so many confusing things. I don't know what to do, especially not knowing anyone, and no funds. So, in short, the guy that helped me is willing to try. I would appreciate any insight and/or assistance you could provide. E