Discrete Mathematics is a broad subject encompassing several formal systems for dealing with discrete quantities. If you are studying Discrete Mathematics as part of a related field, you may wish to follow one of the links below to a streamlined set of core topics that you need. A complete list of Discrete Mathematics topics is given below.
Core Topics for Related Studies 
- Topic:Introductory Discrete Mathematics for Computer Science
- Topic:Discrete Mathematics for Computer Science
Complete List of Subjects 
- Topic:Digital geometry
- Topic:Digital topology
- Topic:Graph theory
- Topic:Information theory
- Topic:Linear algebra
- Topic:Markov chains
- Topic:Number theory
- Partially Ordered Sets
- Topic:Set theory
Until lessons are completed, you may wish to visit wikipedia for more info. There's a lot there - you may wish to start up another pot of coffee.