I have just got a new 9' longboard, it has a 4+1 fin set up which I haven't had before, any information(or links) on how best to use this system would be appreciated. Not sure if you can run a 1,3 or 5 set up due to conditions etc. Thanks in advance.

The quad (4 fin) with the centre empty is a set up for fast horizontal waves such as down the line style waves (think Lennox, Kirra etc) where speed and racing sections are needed and thruster style (3 fin) for vertical surfing on beach breaks and slower waves where your turns are more cutback / pivot orientated.
Big old single fin for cruising.
If your not sure, stick to the 3 fins and when you're ready for your next challenge try the quad set up.