I love knitting,and quilting. I wanted to knit a patchwork quilt,and I was thinking that cotton fabric squares that went with the knitted side would be cool for the backing of the quilt. I just don’t have any ideas how to start? I know I want to knit red,white and blue squares,and the fabric squares would be the same.
Decide what size you would like each square to be. Then choose yarn and work a swatch in the yarn with the needles recommended on the ball band. That’ll help you figure out how many stitches you get per inch and from there you can calculate how many sts to cast on for each square.
Be careful about the type of yarn however since it will have to be washed along with the quilt. Also, depending on the size of the quilt, cotton can be very heavy so you should think about weight as well.
Thank you 
I am going to try a lap quilt.
You might also think about using a slightly more stretchy fabric for the backing. Cotton tends to pull at its seams even when you have it knotted well. Not saying you can’t, only that the lightweight muslin I used once upon a time didn’t work that well and given my druthers, I’d sooner use T-shirt fabric if I were doing it again.