Stem and Leaf Diagram

Question 1

How to write a diagram?

Answer 1

Put different colours for each group of numbers to differentiate them from each other.
Then as you put each number in their section, (for example 22 on the 2 section as simply 2), you cross the numbers coloured to not confuse yourself.

Question 2

Stem

Answer 2

The first digit or digits

E.g. stem of 12 is one.
Stem of 123 is 12