where do I start?

I want to preface this with saying I know nothing. I got the idea to try to build some sort of software that can basically look at a construction blueprint and figure out roughly how much it would cost, or at least help to some extent. I learned a bit of JavaScript a while back, but I don't even know where I would start typing code. Does this sound like something that is possible for somebody's first real project? It doesn't need to work well or anything, I'm not planning on selling it, but it would be very convenient if it did end up working somehow, and it would be a good experience if it's possible to do. Any help about anything would be great. remember, I know nothing.