If you want a quote, you need to provide a more detailed design specification than that.
Do you have a front end design?
What kind of data besides text will tutorial include: images, individual formating, video, etc.
Exact list of fields associated with tutorials.
Exact description of content and functionality of each page, flow between the pages.
From what you described so far, I would charge around $5,000 - $8,000 for a custom backend like that....
"Working web site is not the one that looks the same on common graphical browsers running on desktop computers, but the one that adequately delivers information regardless of device accessing it"