Question

Where do we apply force while walking ?

Answer 1

Your back foot is pushing you forward, so the frictional force on the ground is forward.

Your front foot is (initially) stopping you from falling, so the frictional force on the ground is backward.

Of course every force has an equal and opposite reaction: there are equal and opposite forces on your feet and the ground at their point (area) of contact.

Answer 2

We apply force on the ground...............the force between ground and our shoes is friction.