Hi,
First of all, make sure you get past the point where you just make a WAN out of your LAN. After you're successful and you see that your new WAN port gets an IP and you're able to ping outside network from your router - then you can proceed with configuring it as you like (PPPoE, tag-based VLAN, and so on).
I'm assuming that you tried to do everything at once and maybe configuration will be messed up somewhere. Please reset your router to defaults - just to make sure you start fresh and following the guide try to manage just to get the second WAN working because the guide is correct and should be leading you to fully working solution.
EB.