The D-Wave system accepts problems formulated as binary quadratic models (BQM).
When working with the D-Wave systems and software, you need to first formulate your problem as a BQM. We can formulate many classes of problems as BQMs, such as optimization problems. We can view an optimization problem in terms of objectives and constraints. An objective is something that we want to minimize or maximize, while constraints are rules about which solutions are acceptable.
To learn more about these concepts, and get some hands-on practice creating small BQMs, see the Learn to Formulate Problems section in the D-Wave system documentation.