Is there a Rolex 101 somewhere?

[gperera]

Hello all. I am new to this forum and in looking at posts there is a lot of information that is posted I am not understanding. I am look g to buy a Rolex. Going back and forth between the sea dweller and submariner two tone. I see stuff about "z" serial number, random serial number. Etc. what does all of this mean? Can someone direct to something I can read to learn so I can avoid getting taken? Also is there any guide to like average prices for these watches? I know it has a lot to do with how old they are. Thanks for the help from a newbie!