I need to do a friedman test


I am writing my dissertation and have done several experiments. most of the significancy tests have been done by a specialist for statistics but it takes forever to get new results of him and there is only one thing that is missing.
I had three identical setups and took samples of each after 1, 2 ,3, 24 hours and analysed for the concentration of two elements.
now I need to do a friedman test to test if there is a significant rise of the concentration over time.
could anyone give me a step by step explanation on how to do this?
there are millions of examples on you tube but none of them is similar to my setup and as i am not too stable on statistics i thought i just ask befor getting wrong results.

kind regards,