Amazon's prices are subsidized by EC2/AWS services. (For example, bulk purchasing of internet bandwidth for AWS results in a discount that greatly benefits Amazon's e-commerce need of bandwidth.)

Therefore, your first step is to spend a few billion dollars building datacenters, hiring programmers and product people, and create a competitor to AWS that has approximately equal market share. That should take 5-10 years.

When you are done, you can start your e-commerce system that competes with Amazon's. You'll have the infrastructure that costs about the same (i.e. is similarly subsidized) and you'll have a fair fight.