First of all, if you have a plakat female, why don't you get a plakat male to spawn her with? Just a suggestion....plakats will be easier to sell!
In the pinned section of the betta forum, there is an awesome write up on what you will need and how to go about it.
A one gallon is far too small for breeding (such close quarters, the male will kill her). Try a 5-10 gallon with about 4-5 inches of water.
You'll need LOTS of plants in one side so she can hide, and something liker half a styrafoam cup for him to bubblenest under.
Put him in first and let him get used to the place. Then, you can put her in a flute vase or half of a clear plastic bottle in the tank. Seeing her will give him the incentive to nest.
After he's made a sizable nest and she has breeding stripes and eggs, you can release her and let them go to it. You can leave them in there for a few days (unless he's just really beating her up terrible). Check the nest for eggs..usually when the dad is OBSESSED with the nest, that means eggs.
Take the female out and let the dad do his work until the fry are free swimming and he looks like he wants them for a snack.
Once the fry are bigg enough to have a WC (I think...someone correct me if I'm wrong), you can move them, carefully into a grow out tank.
That, my friend is breeding in short. BUT, please go read the pinned topic as it is full of a lot more info than what I've put here.