Hey again Finn ;)
The exercises I told you about are just typical Natural Horsemanship exercises, not clicker training.
I'll start with the basics, there are 4 ways any creature learns:
1)Negative Punishment - punishment for doing something bad (smack for an attempted bite)
2) Negative Reinforcement- removal of something negative because they did something good (removal of pressure when they do the right thing)
3) Positive Punishment - removal of something positive when they do something wrong (this is more common with people - no TV if you don't do your homework :P)
4) Positive reinforcement - the addition of something positive for doing the right thing (giving a treat for doing a new skill)
So Clicker training is typically mostly Positive reinforcement but some people add in some negative reinforcement too.
Essentially what the clicker does is create a bridge, it tells the horse "at the very moment you heard the click, exactly what you were doing is what I want" and they get a treat or other reward for it.
This isn't as simple as it sounds, it takes work for them to learn that click=treat and time for them to learn to take treats respectfully, but after that your limits are endless with the skills you can teach them.
My unrideable pony is building his list of skills he can do! He can now be lead respectfully (this was a serious issue when we got him), he no longer mugs people when they come in the barn, he no longer kicks or paws, but he'll follow a target, he'll chase and target a foot ball (he's working on learning to fetch), he'll back up about 6-8 steps now, he's learning to give hugs and kisses, he's also working on bowing.
My mare is ride-able so I start with all the basics teaching her (using clicker training) to walk on lead, back up (she's only got 2-3 steps now before she gets unsure if that's what I want), turn toward and away from me on lead without ever invading my space (this was a serious issue for her), she's overcome her horrible phobia of leaving her paddock (this was beyond serious with her, nothing got her out before), she'll target and has just learned how to "Stand" and I can make 2 full circles around her in each direction now :)
So now that her ground work is getting solid I've started working on backing her - so we practiced on the ground the same giving to the bridle exercises I told you about, except I backed it up with Clicker Training. Then I worked on backing her, I've gotten on 4 times now, the first few times were just having me sit up there and letting her get comfortable, with some practice on giving to the bridle mounted. Now she's working on walking with leg pressure. :)
The biggest reason people don't like the idea of clicker training is because they're afraid a horse will become pushy or rude with treats, but if you don't forget the first step and maintain it through all the lessons you'll have a less pushy horse than most ;)
Here are some great links on clicker training and how to, with some helpful videos: Video 1 On The Ground : On Target Training with Shawna Karrasch Step-By-StepTrainingGuide
Here are some great videos on what you can achieve with it
This one is actually someone on this forum, she's one of the best clicker trainers I've seen and has taught me alot!