Your sentence is almost correct! Here's a slightly better way to say it:
Original: This instruction booklet will help you draw step by step.
Corrected: This instruction booklet will help you draw, step by step.
By adding a comma, the sentence becomes clearer and easier to read. It separates the action from the method.
You could also say:
- This instruction booklet will help you learn to draw step by step.
- This booklet will help you draw pictures step by step.
These options are also great and easy to understand for a 7-year-old!