The Load Balancers (ELB) are some pre-configured instances automatically distributing the incoming traffic across multiple EC2 Instances.
Simply drag a load balancer from the Resources panel then drop it outside of the Availability Zones.
You can then link the load balancer to the instances.
At this point, you will be asked to configure the security rules between the load balancer and the target instances.
You can configure the load balancers on the right panel.