It's extremely easy. Cannabis is one of the easiest plants to grow that I've ever grown and I've grown hundreds of different types of plants.
Get some decent soil.
Plant seed.
Give light when it sprouts.
Water sparingly. Overwatering is a common mistake but easily corrected.
Don't overfeed. Many feed their plants an excess of nutrients which causes problems.
Leave it alone and let it grow.
Harvest when done.