Some people, for whatever reason, knit in the round on the inside, with the purls on the outside. Then they flip it inside out.
If you want garter stitch, you would knit one row and purl one row, on the inside if you want.
I'm not sure if shaping is affected if you knit on the inside, I've read that its not. But if you can knit mirror image successfully, I'm sure that would be a minor point to you.