How to create a secure package?

Hi... I have created one package from some of my prefabs in my project. these prefabs have some C# codes in them and what i want is to encrypt these codes like no one can see the actual codes!! I've seen some packages that use ".dll" files and in their code files they just use their own methods. i wanted to build a dll file from my code like what it said in this link http://www.c-sharpcorner.com/article/creating-C-Sharp-class-library-dll-using-visual-studio-net/ but i couldn't get any dll file! What should i do?!!