how to set the contact pair correctly?

I have a question about my subject.

So when i set it, what i need exactly?

I set my boundary condition about which place get received some force.
And i set the contact pair.

there are 3 parts in my modeling. one of them is located between 2 wide plates.
and the upper and bottom plate are getting together to center to push the middle one.

So i set 2 pairs for contact. but there is some error..
I wonder how to set exactly..........
So in order to move the plates to center, i have to set something except setting for force??
just i set the force as 2000N...
please give me some advice.