11.1. ORGANISING A WORK SPACE
When you type, your wrists should be straight (not twisted in or out) and flat (not bent down or up). The way you hold your arms, shoulders, and neck can also contribute to problems.
You should sit with your thighs level, or angled slightly downward, and your feet flat on the floor (or a foot rest). You should sit up straight with your shoulders relaxed, your upper arms at your side, and your forearms horizontal or tilted slightly downward.
A rough rule of thumb is that your knees and elbows should form right angles. Your keyboard should be level or have a slight negative tilt (top row lower than the bottom row).
The top of your screen should be at about eye level.
Adjust the position of your keyboard and monitor to accommodate your body, not vice versa.
I did a drawing but it was not possible to put here, If someone is interesting in look at it write me and I send it.