None, but it helps if your dog already knows what the clicker means.
Start in a place where your dog finds it easy to relax.
Place the treats on the mat if you have one and it will cause your dog to get up, or toss the treats far enough away that your dog has to get up.
PLEASE DO NOT USE THE CUE (DOWN) YET. We want to be sure your dog is doing the behavior immediately and consistently before we add the cue.
Your dog should be offering to down without you asking for anything. Your dog may not stay very long, but he should lay down for a few seconds.
Do not force or cajole your dog in any way. This will slow down (or even stop) their progress.