Step 7: Don't panic
Each key gets one spring, even if it's a big one. You can look at your keyboard, the electrical circuitry and the backside of the keys to figure it out for yourself, but here's a shortcut. Just follow the pattern in this pic and you should be fine.
By the way, here's the backside of the long Enter and + keys from the number pad. The spring goes in the top notch, not the fully enclosed one.