All you need to do is fill the canister with water, and plug it in. But make sure the both the input and output are both underwater. To make your life much easier you can buy the priming bulb for $11 which you can use to pump water manually into the canister, this also prevents annoying air bubbles from being trapped inside the canister.
As for Classics vs Ecco. Classics are a superior and proven. Classics are much powerful, reliable(some people have 25 year old canisters still in good shape), they have a spraybar, and are much quieter than the Ecco's.