1. Goto http://www.blackberry.com/support/index.shtml
2. Under the heading "downloads" select "service packs"
3. Select "Blackberry Desktop Software 4.1" in the pulldown menu
4. Choose service pack 1 (English) or service pack 1 (multilingual) if required
5. Now download this to your pc and run the installation

Now you need to download the firmware upgrade to support your handset.
Select your network from the list below to be taken to their firmware page then choose the newest firmware version for your model :