How to append an item to data.addRows

[Soulstice]

I am very new to coding and I am self taught but I don't understand how I would add a row to the graph once its already been drawn. I want to add variables to a pie chart, the variables are called tempName and tempTime. As such I want add them like such: [tempName, tempTime] however I am unaware of how to put this into the code properly such that it reads it. If I need to clarify moreso I would be happy to, I'm sorry if this is a simple question.