Hi,
8 1/2 x 14 is legal size paper. If you do not have any, I can send you some, of you can buy a couple sheets at Staples for a few cents a piece.
The paper should be at least 20lb paper. If it is too thin then there could be a problem, but thicker is fine. If you wanted to use thick stuff, I'll bind that in too.
It should look like it was assembled from across the globe, so even different color papers are fine. The only thing is that the pages are no smaller than 8 1/2 x 14.
That being said, if you are submitting only one page, there is no reason that you could not use a letter size page, and cut it down to 8 1/2 x 7, but the finished product needs to be taller than it is wide, or it will go in sideways.
Also, please leave some space around it as I will have to trim the top, bottom and right sides slightly.
Bill