You are doing stockinette with seed stitch borders. The center stockinette stitches are done by knitting on one side and purling on the other. If you goof and do the opposite it will reverse. You'll have rip back to before the mistake and doing it correctly.
The knit stitches are the ones that look like a V. The purl stitches are the bumpy side..they look like a scarf on backwards kind of. Here's a sample of what they look like. It's important to learn.