how do i prevent the first person controller passing through wall?

i imported a fbx file from google sketchup. when i placed the controller it fell then i started to replace the gravity of the controller but when i moved the controller into walls it pass through? what should i do? can someone help me?

Controllers run into colliders. Add a ‘mesh collider’ component to your model and see if it helps. If not you’ll want to manually place primitive colliders around.