1. Navigate to Firewall | Traffic Shaper.
2. Click on the Wizards tab.
3. Click on the Multiple Lan/Wan link:

4. Enter the Number of WAN type connections and the Number of LAN type connections in the appropriate text fields. Leave the latter set to 1 to apply traffic shaping only to LAN interface traffic:

5. Click on the Next button.
6. On the next page, select the interface and scheduling algorithm for each of the LAN and WAN interfaces. If you only have one LAN interface, no changes need to be made here:

7. Select the correct upload and download bandwidth in the Upload and Download text fields. You can select the appropriate upload and download rates in the corresponding drop-down menus (choices are Kbit/s, Mbits/s, and Gbits/s):

8. Click on the Next button.
9. Check the Prioritize Voice over IP traffic checkbox.
10. Keep the Provider set to Generic (Skype isn't listed):

11. In the text fields for the WAN and LAN interfaces, enter the amount of upload and download bandwidth you want to reserve for Skype calls. A high definition Skype video call requires at least 1.2 Mbits/s of both upload and download bandwidth, so you'll likely want to reserve at least that much and possibly more, depending on how many simultaneous Skype calls you anticipate occurring on your network.
12. Click on the Next button when done.

13. The next page controls settings for the Penalty Box, which allows you to penalize an IP address or alias. Since we don't need to penalize anyone, click on the Next button:

14. The next page controls settings for peer-to-peer networking. Check the Lower priority of Peer-to-Peer networking checkbox:

15. Check the When enabled, all uncategorized traffic is fed to the p2p queue checkbox. Enter 10 into the Bandwidth edit box to limit P2P traffic to 10% of the total bandwidth:

16. In the Enable/Disable specific P2P protocols section, check the BitTorrent checkbox to enable the BitTorrent protocol:

17. Click on the Next button.
18. The next page of the wizard is for prioritizing network games. Since we don't want to prioritize any games, click on the Next button.
19. The next page of the wizard is for raising and lowering the priority of software, such as remote desktop applications and messengers. Since we don't want to raise or lower the priority of these applications, click on the Next button.
20. We have now reached the end of the wizard. Click on the Finish button to load the new profile:

21. You will now be redirected to the Filter Reload page at Status | Filter Reload. The contents of this page should confirm that the NAT and firewall rules have reloaded: