How to configure two 2 Dell 3524s to provide redundancy for servers

We are working with multiple servers, all of it with dual NICs. To provide connectivity between the servers to the firewall LAN interface, we are currently using a single unmanaged switch. We have two Dell 3524 switches and two SonicWall NSA 4500s. How should we set up the two switches and how should we connect them? We want to be covered just in case one of the switches or firewalls go down for any reason. Any help would be greatly appreciated.
