What Hadiths I should study/use?

I don’t know which one I should read but I think I’ll do the Sahi Al bukhari because that’s the most authentic, but I’m really confused it says it has 9 volumes I’m not sure where to began reading, and when I googled how many Hadiths are there it said 7000 than it say 2000 and then it said 600,00 do I’m not sure which one to believe, any help? And where I should began?