How to call the blend apace in character blueprint

So I am creating an npc character and i had selected it in the mesh of a new character blueprint and had created a new blendspace 2d that contains two animations the first is the walk and the second is the run the both are in place animation what i want is that when my character enters the collision box i made in the character blueprint the animation changes from walk to run with blending between them so how can i call the blendspace and give it a variable to change these animations
Thanks for you in advance