What things did Sherlock Holmes notice in the cozy room in the story of yellow face?

is basically a good source of getting and others by what you know for example if someone asked a question and you know the answer you could answer it and get some points or if you need on a question you could make a post about it and wait till someone answers it or just look up the question and see if someone else has asked about it

Ihaven't read it but i hope u find ya answer