In the Derivative mode (there are also Grad, Div, Curl and Laplacian modes), just :
- type the expression to derivate in the "Expression" field, using the syntax shown in "Help";
- choose which variable with respect to derivative in "Var.1" field, and the number of multiple derivatives (e.g. 2 for second derivative) in "#" field. For partial derivatives, "Var.2" and "Var.3" can also be used.
- type enter in any field to calculate;
- see the "Settings" for many options.

zurrain101, "Derivative" does not solve equations. If you tell me exactly what you want maybe SymPy can be useful to make a sequence of calculations using derivatives, etc.

And try to learn and calculate by hand in your Calculus classes. This software is an aid to calculate more difficult derivatives and differential operators (gradient, etc).

Feel free to tell me your opinion, make questions, etc.