If you are not talking about a true moebius then you just cast on about 60 to 70 stitches on circ needles, give one twist and join in the round. I always knit the first two stitches together to secure it. You just continue knitting till you get it the size you want. It turns out very pretty. As you go along you just work through the twist, kind of moving it along in front of you, leave enough yarn to cast off and you are done. I have made one like this and it turned out very pretty.