transmission

I have a 1990 honda accord ex. When I shift into gear I hear a popping noise coming from the break and the gear shifting "thingy", also I can drive it approximately 1/2 a block and it just locks on me. Have to turn it off and start again to be able to drive 1/2 a block.

There is also a hissing sound coming from the engine part when stopped, but when driving it goes away.

Changed transmission fluid and added Lucas Transmission Fix it, but problem still persists. Son in law states that when the fluid goes up it is when it won't shift. Any suggestions?