How does the cell membrane change in appearance after exposure to the NaCl?
There are some different ways of interpreting your question, but I'm taking it to mean that you have a cell which is placed into a solution of salt water.
The salt water will cause water to leave the cell - making the cell look like it is shrinking. The movement of water through the membrane (in this case going out of the cell) is called osmosis .
Here is a video which shows this with red onion cells and uses an analogy to help explain the changed in the membrane.
Hope this helps!