concept question about dll

My boss asks me to create a dll 开发者_Go百科file using C++. The dll file needs to do the following:

1. create a blank area in Window
2. create some simple shapes (for an example, a rectangle) on the blank area
3. control the locations of the shapes in the blank area

I am new to C++, so please correct me if my understand is incorrect Dll is a binary file, does it allow to call other libraries to create the blank area?

the DLL should be called from some executable and the dll can also call other dll's functions. While creating a dll, you need to create an executable to test the dll, and you can use other dll by dynamically loading or using its .lib in the project.