Burton Blender Snowboard - Women's - 2008 BCS

This board would be great for a beginner because of the opportunity it would give you to advance your skill level. It's a great board, hence the Transworld Snowboarding Good Wood award from 2009 that is received. So it's LEGIT! It is however a freestyle board which means it's built more for the terrain park, therefore the edges are angled up a few degrees so you won't catch an edge on a rail and faceplant for example. This also means you won't be able to carve as easily in hardpacked and icy conditions. Given that you're just a beginner, you probably won't know much difference anyways, which is perfectly fine. I just want you to know what you're purchasing.
As far as size goes, you could get anything from a 140-150. This again depends on what you want to do. Longer boards are faster, more stable at high speeds, and better in powder. Shorter boards are easier to control, turn, and maneuver.
If I were you, considering that you're still somewhat of a beginner, I would shoot for something around 145. So a 143-147. I definitely wouldn't go any longer than 147 for sure! That's almost too long in my opinion. My g/f is 5'6" 115 and rides a 143 and loves it, and she is pretty decent.
I personally prefer shorter boards simply because they are easy to control and handle.