Have you read the manual ?
[quote:hdixusfs]Set animation
Change the currently playing animation to another animation. Animations are identified by their name (case insensitive). The new animation can either play from the beginning or from the same frame number as the last animation was on (current frame).
In the parameter box it states:
"The name of the animation to set"
So if you have an animation called 'BossWalk' for instance, then you would set the animation name to
"BossWalk"