When casting on for a project that is knit in the round the instructions often say to “join” the stitches after you have cast them on.
1: Cast on the required number of stitches onto double pointed needles or a circular needle.
2: Bring the first stitch you cast on around in a circle to next to the last cast on stitch.
3: Check that the stitches aren’t twisted around the needles
4: Bring the yarn to the front of your work and slip the first stitch from the right hand needle onto the left hand needle.
5: Take the yarn to the back of your work.
6: Slip the stitch back onto the right hand needle.
You have now joined your stitches, ready for knitting in the round.