your back should be straight and your chair should be puched in so that you hands are at an angle a little less then 90 degrees
Off the table or laptop, and at a >90 angle so it your hands were on top of each other on the keyboard, it would form a rhombus (assuming your arms are the same length).
on your shoulders
they should be flat in frint of you.
when typing, you should have a straight posture.
You should not look at the keys while you are typing.
Vertically
Your feet should be flat on the ground, or in a comfortable posistion so you can concentrate when typing.
Sitting
very carfully
We HaVe ElBoWs BeCaUsE We MuSt..
If you are touch-typing, your eyes should be on the 3rd to 5th word beyond what you are currently typing.
Most elbows should twist on the regulator. If it does not, your best bet would be to weld it on, or send it back to the manufacture. Luckily though elbows are meant to be replaced after some time so the task should be manageable.
Giraffes don't have elbows.
It might mean there is a button positioned on the left, and another button positioned on the right, and you should not push the button on the right.