Doors and Windows - Converting a window seat into a toy box

I have a boxed out window. It already has a window seat that has a plywood top.My childs room is small and I would like to know how I could form the extra space into a window seat that lifts so I can use it for my childs toybox. Please help me and give me as much information as possible. I have never done anything like this, but am so willing to learn. Thanks alot:)

the hardest part is already done :)

1 you will need to pry off the plywood top careful not to damage it so you can reuse it

2 if you cannot get it off in a salvagable manner use it as a template on a new piece of plywood to cut out the shape

3 you will need several hinges depending on the width possibly 3 or 4

4 for ease of installation id buy mortise free hinges unless you have a router or are handy with a chisel

5 you can hinge the plywood top to form the toy box lid assuming your plywood is rather thick if not trace it and double the lid so its sturdier

hope this helps----josh