Every maneuver has a specified initiation action, so you initiate and use the maneuvers as you go through the fight. When you enter a fight as a warblade, whatever maneuvers you have readied are immediately available for use. If you want to change which Y maneuvers you have readied, it takes 5 minutes, unless you have the Adaptive Style feat. You prepare a selection of Y of the maneuvers that you know, and those maneuvers are available for you to use in a fight. You know X maneuvers, determined by your level. If you have any other / more specific questions, I'll be happy to try and answer them. You can do this as a swift action, provided that the swift action is followed either by a melee attack or doing nothing with that round's standard action (you don't get a move action). When you use one, it becomes exhausted, and you can't use that one again before refreshing your maneuvers. You start any encounter with all of your readied maneuvers available. Understanding the 'refresh' mechanic is important to understanding how the class works. You are not limited in the number of times per day you can use maneuvers, since you can 'refresh' used ones an unlimited number of times. You can change which maneuvers you have readied over the course of 5 minutes of exercise at any time. However, there are several important differences between these maneuvers and spells. You then get to have some number of those 'readied' for use, like a cleric or druid would prepare spells for the day. There are some limits on what level maneuvers (1/2 class level rounded up) and what 'type' of maneuvers you can take (you can take from Diamond Mind, Iron Heart, Stone Dragon, Tiger Claw, and White Raven). At every other level or so you can learn a new maneuver, basically like adding it to your spell list.

An analogy that I like is thinking about it like a druid or cleric. I can try, since I'm actually playing one right now.

Warblade 3.5 dndtools