Unable to find Documentation on YOLOv5 Classification

Hi everyone!
Im using YOLOv5 for classification of facial expression. It is working fine but im new in this domain so im having trouble understanding some lines of code. Notebook given by roboflow tells what to paste in their code but not explains what is happening. Is there any proper documentation regarding what is happening in each sell. After running that sell im able to understand what is really going on but if i want to change code, im facing deficulty because of lack of information.

In the figure attached, it is only testing on one folder out of seven. Also im unable to understand to test it on all folders by changing code in it. In first line if i replace -1 with -2, i comes out of sad folder(last line of figure) but than it shows there are no folders in that directory but there are seven classes in it.