evening
I will draw up a picture tommorow to show you what a header is, how to support everything and everything you need to know if you would like.
you don't need any 3/4" plywood. if the opening is to be about 6' I would use a 3 ply 2x10 header. 2 ply is probably enough but I don't know what is above.
I have been a builder for 16 years. I actually just built the new retirement home in Naniamo right above the firehouse bar. (good sushi)
