Relational Database using Drupal 7

Hi. I am looking at Drupal for the first time. So far I cannot help but be impressed, but like most Newbies getting to grips with Drupal I am finding it quite challenging.
I have a personal project in mind as a starting point to learn. I think I can manage the basic static pages and have looked at standard themes.
The site will require a paid members area accessing two relational databases. One will be a quiz of 30 questions/multi-choice answers based on a random selection from and increasing question database with a % achieved certificate at the end of it. The second will be a series of one to many relationships with a photo upload facility. Print out will be required. Traffic will be light as records will be kept and only read, copied or duplicated occasionally
The site will be a fundraiser so I will need to understand how users can pay. (The idea is to charge monthly storage for each set of members records held)
Compared to this, knocking out a relational database on my PC is relatively easy.
How can I use Drupal to create a relational database and where do I start looking for guidance?
Thanks Guys