For a complete tutorial on how to use vpcs in gns3 you can check out Chris's blog here
This post will only help if you're having issues with connecting your vpcs to your routers in gns3.
Did you get this message when u tried connecting router's ethernet port in gns3 to one your vpcs?

206 - unable to create UDP NIO

steps to solve this

1. Start a new project if you're working on a simple one.
2. Otherwise, go to the "working directory"   ---->      where you save your projects and delete your project while your gns3 is still open with the current project.
3. Now you CAN connect the router to your vpcs, check that and  save your project.
   
4. Try to avoid switches in between vpcs and routers when verifying communication between the router and vpcs.
   
5. Once you're connected and made sure  vpc and router communicate, by pinging from either of them, you can add a switch in between.
   

WATCH!

• Careful with the Lport and Rport entries: vpc1 gets Lport: 30000, ip: 127.0.0.1, Rport: 20000
• If Lport: 30000, Rport:20000 doesn't work try with different values, you can go up to vpc9 Lport: 30008, Rport:20008

With the " 206 - unable to create UDP NIO " you'll not be able to connect your router directly to your vpc but you can connect them through a Ethernet switch in between but there won't be any communication. Thats why, to be sure, connect your vpc to your router directly and if it connects, well and good if it doesn't then you wanna start a new project altogether or do steps 2, 3.
I dont think it really matters if I open vpcs first or the gns3 first. In my video i started vpcs after gns3, so.
Watch the video below. Its a simple topology, one router and one vpcs. you'll see how the error shows up and how we can avoid that.

Configuration:
router:
f 0/0 - 192.168.2.1 255.255.255.0
vpcs
ip 192.168.2.2       192.168.2.1     24
(gateway: is the router's f0/0 192.168.2.1).

I will try to help , ask questions in the comments please. Thanks..  video here( Big screen ) or right below.