OK, so you want to make a border with corner blocks...
If your quilt is 36" by 20" then you need two border strips the width you want (eg 5" + seam allowance) x 36 1/2" and two strips same width x 20 1/2". Your corner blocks need to be squares the same size as the width of your border + seam allowance.
For the border fabric - you can cut across the width so the long borders need two strips of the width (if we're going with 5" wide this means 11") and the short borders, you can get out of one width, so you need 16 1/2", so buy half a yard.
If you go with 5" wide borders, your finished quilt will be 41" x 25" so you can cut the backing across the width, therefore you need 25" of fabric BUT buy more because you should always leave your batting and backing a couple of inches bigger when you make your sandwich and trim up after you've quilted; you also need 4 squares for the corner blocks of your border so if you buy a yard you'll have plenty.
For the binding - the circumference of your quilt will be 2 x width + 2 x length, so 132". If you cut the binding across the fabric width, you'll get 44" lengths which you then join together, so you'll need 3 widths + seam allowances, so allow 4 widths. You make double binding 2 1/2" wide so you need 10" of fabric. If you bind with the backing fabric, then I'd get a yard and a quarter, which should be enough for backing, corner blocks and binding.
Your batting needs to be a couple of inches larger all round than your quilt (for trimming up after quilting) so say 43" x 27".
So in summary, half a yard of your white border fabric, one and a half yards for backing, corner blocks and binding and batting of 43" x 27" - you can get it in precut packages, crib size should do the trick (this is usually 45" x 60" so you'll have some over for your next project :wink: :D )
K x
PS Just ask if you have any questions about making your 'quilt sandwich' and let us know when your ready to bind!