The first time around, I made the mistake of copying my code exactly,while I should have duplicated each square at that point. If you're generating your own pattern, try to remember to double the stiches - it makes it much easier when working! (the uploaded pattern has been updated,and shows it as it should be knit)
Step 1: Knit the Piece
The pattern I created has a garter stitch border, created by knitting 3 rows before beginning the pattern, and then adding a simple "knit 3" at the start and end of each row - I've allowed for this in the 60 stitch cast on.
The pattern here was created using the chart drawn up in excel, that was then copied into powerpoint, written instructions added, and saved as a pdf.