New here! Questions about the site.

[Histep]

I have read through all the FAQ's and have not seen this. Is there a sticky thread somewhere that explains how the site actually works? It seems like every time I click on something, I get a different view. Maybe I need the instruction book.
In the lists, why are some titles in bold print and others are not?
At the top,if I click on "threads" or "thread starter", what is the new view that I am actually seeing? If I reply in an older thread, does it move to the Top?
Thanks for your help, this is all a little fuzzy to me.

HERB