Mud Minnow Traps

I cannot figure out where these traps are meant to go. I thought you put them in the bottom of the stream where a little creek leaves the mud flats on the low tide and you catch all the outgoing minnows and vice versa when the tide comes back in? I am using dog food for bait and always catch many little one inch shrimps instead of minnows. Can someone give me a tutorial on where I can drop these from the bank? I've watched youtube videos and feel like I'm doing what the guys in the videos do but i dont catch any. Thanks for any help!