get a hold of a book called "Sign Structures and Foundations" by Peter Horsley
that will get you started with part of it
the actual electrical part, depending on local laws you may need to be UL certified, licensed electrician, etc. to even build them, or sometimes to install them
electrical signage is one of the hardest parts of the sign industry, just below carved dimensional signs in my opinion
it is alot more complicated then just grabbing a book and reading it like i am suggesting, but if you have a real desire to learn it, it is a good starting point.