Even experienced pilots still occasionally have problems with the flare at night (it is difficult to estimate your height in poor visibility). If you butcher a landing, go around and practice a few more times.
You should never let the airspeed bleed under any condition on approach, but this is especially true at night. Add power and lower the nose, but whatever you do NEVER let the airspeed bleed off near the ground at night.
It's important to stabilise your approach on finals; fly a slightly larger circuit, this gives you more time to get set up. Use power and avoid gliding approaches until you are more experienced.