In transcribing discourses, there are some conventional symbols for overlap, pause, prosody, non-linguistic sound like laughing, and so on. There are different traditions out there, and you are not required to strictly follow a particular set of rules in your final project. However, it is a good practice to try using them. I recommend Du Bois’ page for this purpose.

http://www.linguistics.ucsb.edu/projects/transcription/representing.html

Good luck!