In my pattern I used foundation double crochet, and I recommended putting a stitch marker into the very first ch worked (you start with a ch4, then work back into that first ch). I recommend keeping that stitch marker while working the entire scarf or wrap. It helps you realise when you have completed a full round. In this method of infinity work, you first work along the top of the stitches, but when you come back to your stitch marker, the twist means that you are then working into the bottom of that foundation row. How? Well, read on. ;)
So, when you reach your required number of stitches, you should have two ends the same length. Take great care doing this (I managed to get my brain in a twist, but then again I've got a cold and I'm 8.5 months pregnant lol). With your work lying flat, take one side and flip it over so that the bottom becomes the top. See below. The stitch marker was at the bottom when I finished working the round, but I have flipped it over so that now it sits at the top. This is a half twist of the scarf.
Now, slip stitch into that first chain (ie the one with the stitch marker).
Now, work along those initial chain stitches using slip stitches until you reach the third one.
You can see where the red end has now overlapped the blue end in a way as I've worked the slip stitches along those chains. Now, being very careful not to flip your work, rotate it so that you can slip stitch into the bottom of the last foundation double crochet that you worked. In effect, you are joining the other side of the ends.
Here I am back at the "beginning" point. I've worked all along one side, but as I come back to the stitch marker, the next stitches presented to me to work are actually the opposite side of where I started. The hook is pointing at where I started with the red stitches.
So, I hope that this has all made sense to you, and you're ready and raring to go and try this method of working infinity style garments.