It's very easy to do.
1. Download the updates from the Spectrasonics web site and place them anywhere on your HD.
2. Unzip them to reveal the setup icon inside them.
3. Double click the setup icon and it will automatically install the updates in the correct Omni directories (make sure you installed Omni in the default directory or otherwise you will need to set the update directory manually).
4. You can now delete the zipped files you downloaded in the beginning.