People, I decided to start my acquaintance with DC comics and so could you tell me where I can get the most complete chronology of comics?(from the very first to the very last; including little-known characters)
Don't do that. It doesn't actually teach you anything about comics. The first comics were just short, independent stories with little character development. There are thousands of little known characters. And thousands of characters that are little known to some, but not us. This is a company which published thousands of titles for over 80 years. And it's also several other companies. You can't get into it by starting at #1 like one would with, say, Naruto or The Walking Dead.
Instead, look for a character you want to learn more about and see if we've got Recommended Reading on it. 90% of everything is crap, and you'd waste a lot of money on that, which would spoil any enjoyment you wish to have.
I was able to read Nightwing’s tie-in with Death of the Family and Court of Owls and not be confused (that doesn’t mean this stuff is fun, I’m also reading the Ric Grayson arc without being confused, some of this stuff is bad, no matter if you’re confused or not).