Unless you spend a lot of time at the UNIX command line or are involved in computer programming, you are unlikely to encounter these keys very frequently. The characters on these keys are the tilde (~), backtick (`), pipe (|) and the backslash (\).
Still, you wouldn't be a complete touch typist without having them under your belt, so let's learn them! We're only talking about two more keys, after all.
Both of these keys are accessed with the pinky finger in an extended position, with the pipe/backslash key being three(!) keys to the right of its natural position on the third row. In other words, it's a REALLY big stretch to reach that key. Try to move your hand as little as possible (or not at all) to reach it; let your baby finger do all the heavy lifting.
Personally I kind of enjoy using this key, since the huuuuge stretch makes it feel so different from every other key!
It's hard at first to do without looking, but you can with just a little practice!
I've mixed in some home row letters in this exercise to ensure you're actually reaching for them from the home row, not just cheating by camping out on them the whole time!