A sharp (or A#) is the exact same as B flat (or Bb). It doesn't matter which of those names you use, you'll always be referring to the same note. It's just two sides of the same coin, really. I generally prefer to use "flat" because that's what I see most frequently on tabs, but my tuner uses "sharp" instead, but when you remember it, it's not that hard. I do understand your confusion, though. It took me some time to learn too (and by that, I mean at least half a year).