Here is the workflow we recommend for creating a website from start to finish. We then have many how to documents, solution recipes, etc. in the Support section of our website, as one of our Community Experts mentioned. These will help you with specific steps for each product. Then if you run into issues, you can use technical support (via this forum) to help you with your questions. It is difficult to provide step by step instructions more in-depth than the workflow I link to above because every website is going to be quite different - as you mention, you need to highly customize yours.
However, to get started, I would suggest beginning with our free database. Then if you want to follow the workflow suggested by our Community Experts, use this how to document to walk you through the steps of creating an admin backend. Post questions in the product forums as you need assistance. Both our technical support team and members of our community will be able to help you.