Let's try this way...
Looking from the bottom the faces you should make one are these shown bellow:
![Click to view image](https://s25.postimg.org/jwsu1zqfj/bridge-1.png)
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:
![Click to view image](https://s25.postimg.org/tu3uv2l6n/bridge-2.png)
In your image both selections are facing the camera view.
Looking from the bottom the faces you should make one are these shown bellow:
![Click to view image](https://s25.postimg.org/jwsu1zqfj/bridge-1.png)
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:
![Click to view image](https://s25.postimg.org/tu3uv2l6n/bridge-2.png)
In your image both selections are facing the camera view.
![Wink Wink](https://www.wings3d.com/forum/images/smilies/wink.png)