Hay loopers
That is one of those tree in the middle of the forest questions where there are a lot of different ways of doing it if you don’t know what the forest looks like.
As a primer let Zak tell you everything you need to know before playing with the tree 
As a direct answer to the question the most common way of blending is by using an animation graph as part of a state machine and add a transition argument that gets you in and out of one state into another.
If you don’t want to watch all of the videos, I would suggest that you do becasue you wil be back asking questions ;), 10- Building the AnimGraph is what your looking for