hi gail! since ive never done one before i thought i was going to use all 9 in each block. am i wrong? i know there is no right or wrong i'm just confused.
You can certainly use all 9 in each block. You will need to decide whether you want each block to be the same, in which case the same squares will remain whole in every block. If you want more variance in your quilt, you can rotate the fabrics in the 9 patches so that different fabrics remain whole in each block. Just advance each square one space in each 9 patch. So sq. 1 becomes sq. 2, etc. and sq. 9 becomes sq. 1.
To know how many squares of each fabric you must cut, first you have to decide on the size of quilt you want to make. Using squares cut at 5.5", each block will end up around 14". A lap throw could be 3 blocks by 4 blocks, where a twin might be 4 blocks x 5 blocks. So your quilt would be 56x70 plus sashing and/or borders. For the 4x5 blocks, you would need to cut 20 squares from each fabric, plus your sashings/borders, and backing. For the throw, you would need to cut 12 squares from each fabric. Basically, you need one square of each fabric in each block. So count how many blocks you need and that is how many squares of each fabric you will need.
For me, it often helps to plan it out on graph paper.