Since your FS9 was recently purchased, you may already have an updated copy.
I bought my FS9 just over a year ago and it's 9.1 out of the box.
Here's a copy and paste from the site containing the update to determine if you need it:
To determine if you need the Microsoft® Flight Simulator 2004: A Century of Flight (UPDATE):
1. Run Flight Simulator 2004.
2. Click Fly Now!
3. Press ALT to display the menu bar.
4. Click About Microsoft Flight Simulator on the Help menu.
5. Check the version number in the About Microsoft Flight Simulator dialog box. If the version number is 9.0 we recommend installing the update.
After updating, the version number for Flight Simulator 2004 will be 9.1.