If you open a .cs file, you can edit it. If you open a .dll file, you can see all sorts of methods.
If you want to code something, goto "file"(I don't know actually), then "new project", and choose your stuff.
If you want to make a mcdzienny command, make a new project and then empty project or class libary.
If you want the skeleton class, generate it with MCDzienny, right click your project, click "add existing item", and search your generated class.
You can add references in VS 2012, it makes coding much, much more easier(you can see methods, how they work, spelling correction, directly errors, etc.). Right click your project, click "add reference", then "Browse", then search your MCDzienny.dll. You added a reference!
In cmds your reference is already been usen(namespace MCDzienny).
If else, type this in the using fields in your code: "using MCDzienny ".
I hope this helps!