Welcome to the forum.  Since you've played guitar for years, you may be able to read music (some guitar players can, some can't) and have a pretty good understanding of music theory. That's a big head start over someone who has to start from scratch.  

Instrument-wise, I think you'll find, as I have, that while both the guitar and fiddle have strings, that's about the end of the similarity. There are a lot of new things to learn and master when you start playing fiddle.  Fortunately, they're all fun -- even if somewhat daunting.  

You've come to the right place though, everybody here is more than willing to help and very friendly and supportive, which makes this a truly great learning resource for those of us who are guitar players.

Let the journey begin.