Let's try this way...
Looking from the bottom the faces you should make one are these shown bellow:
Now, to help you to understand where is the selection compared to your image notice the coloured table legs only the inner faces for bridge are selected:
In your image both selections are facing the camera view.
Looking from the bottom the faces you should make one are these shown bellow:
Now, to help you to understand where is the selection compared to your image notice the coloured table legs only the inner faces for bridge are selected:
In your image both selections are facing the camera view.