Introduction to Programming in C
To get started, I recommend working through Jens Gustedt's Modern C textbook. It is available online, free of charge, or can bought in any decend bookshop.
If you prefer watching video tutorials rather than working through a book, I recommend C Programming for Beginners.
For learning any programming language it is most important to write your own code. As a student of HTL Bulme, you may use the provided SSH access to our sandbox server.
The following interactive presentations provide a good starting point for self-study as well.