Ed's Go to Ed's website, click canoe seats, there's a picture of one of theirs already installed. You just cut it to fit, then suspend it from the gunwhale with through-bolts, using the spacers to make it more rigid. I would do it differently, but I need to find another part so I can show you. I'll be back if I find it.
Bracket I would use these, this is probably the way your other seats are installed