On defence it will come down to a couple of things, including what defensive system your coaches want to run.
The standard is for the 9 to sit behind the ruck organising the left and right ruck defence, and then acting like a sweeper once the ball is moved away, similar on Lineouts.
On scrums there are a couple of ways to play it, the first is follow the ball around and hassle the 9/8 as they pick up, the other is to drop off the scrum and make the extra blindside defender. It will come down to your coaches preference.
In attack again your coaches will decide if you play across the pitch or backwards and forwards, so a lot of it will be taken care of for you, but in attack aim to get to each breakdown early and play it from there; apart from hitting your 10 you can look to pop off to a forward coming around the corner/on a short line, or have a dart yourself. Try not to get pulled into the ruck, send forwards in if your ball isn't coming and try not to run slow ball, set your forwards for a pick and go.
The key to a good 9 in attack (and defence) is making sure you can communicate and get organised on the fly, but essentially in this day and age as long as you are: Getting to the breakdown first and then organising, having occasional snipes (not all the time) and tracking the ball in broken play you'll be there or there about.
Also try and work on your defensive box kicking - it can really help your fly half out if you are able to take some pressure off by hoisting a decent box/clearance kick.
good luck, it's a fun position to play.