I am trying to find some database tutorials,books and similar, since I have started this course in college, and received some material, but it is really hard to manage through all the info on the net. I searched through the questions on the site but didn't find any. Thankfull for all your input.
It sounds like you are looking for something on an overview level rather than a practical level. If you are interested in learning about Oracle databases from a practical level, there is no better place to start than the Oracle Concepts Guide.
As Dynamo already commented, it might be better if you specify which aspect of "databases" you are interested in.
If it happens to be database design, I can strongly recommend "Beginning Database Design" by Clare Churcher. It's a very accessible book, but points you into the correct direction ("normalization").
A source more valuable than this website here should be the lecturer of the course you are taking (or the teaching assistant if there are exercises). Did you ask her/him? (If you don't trust the lecturer for this question, you should consider dropping the course.)
Clear and concise introduction to the SQL language: The Language of SQL
Not for basic concepts but for technical references, I always prefer the sites from the DBMS itself. They are all really good IMO and most of them have a "Getting Started" or "Beginner" section.
Be sure to check out the comments (if available). Sometimes, a real gem is hidden there.
PostgreSQL is a good choice because is really open source!
The project have a great documentation, really simple and understandable. Also, the community is very reliable and dedicated providing a great maturity to the project.
A good and a complete option to start in database world.
If you are a kind of person that like books, I could suggest: http://www.postgresql.org/docs/books/