, - this symbol lets the reader know to pause and breathe
. - this symbol lets the reader know that you have finished one thought and would like to start another
? - this interrogative symbol goes at the end of a question to distinguish if from a statement
Here is an example, for your reading pleasure. Could you tell when I finished one thought and started another (and did you take the time to pause and breathe)? Now you try it. Punctuate your statements with useful symbols. People may even find that they actually want to help you. Cheers!