Climbing a frozen waterfall is one of the strangest and best things you can do in a winter. The route you climb might not have existed a month ago and may be gone in a fortnight. You swing a tool, it bites, and you are standing on two points of steel on something that was falling water in October. Most people who try it once are hooked by lunchtime.
It is also far more accessible than it looks. You don't need to be a rock climber, and you don't need to be strong. Beginner days run on single-pitch ice with an IFMGA guide, top-roped, with several laps at increasing angles as the day goes on.
You typically learn:
Tool technique. How to hold the ice axes, swing them efficiently and climb without getting tired.
Footwork. Front-pointing means kicking once and trusting two points of steel, heels low. It feels wrong and it is correct, and the moment you believe it the climbing gets much easier. Guides often have you climb a short section on feet alone first, which is the fastest way to learn it.
Reading ice. Clear blue ice, aerated white ice, detached curtains — where a screw will hold and where it will spin.
Screws and belays. Placing a screw while hanging from one tool, building a two-screw belay, and threading a V-thread for the way down.
Staying warm. Managing gloves and cold hands properly is a genuine skill.
Leading an ice climb is a separate progression and is not usually attempted on day one.
Typical locations in Chamonix are the Bérard waterfall in Le Buet/Vallorcine, or sometimes the guide will take you on a short drive to Cogne, in Valle d'Aosta, Italy.