just follow the tutorial in the helpfile on setting a walk path, it's a really good tutorial and its easier to understand once you have done it once or twice.
It will teach you
how to lay a walk path
vary the distance between footsteps to control the pace of the walk
and change the impact of each step to control the characteristics of the walk so it could be a tippy toe, a sneak, or a shuffle etc
It's definately worth while taking your time to implement and understand how to complete the walk cycle as you'll have to practice for a couple of weeks to make understanding it totally instinctive to apply to your character so don't rush it.
Getting a good understanding of the walk cycle is extremely important if ever you want to go to the next level and begin to use motion builder because the principles are extremly similiar.
don't forget to put up your attempts up for us to look at