i just learned how to knit in the round this weekend. i just don't know how to add a new skein on
You can tie a knot in the two ends and either leave it, or loosen it up and weave the ends in later. You can knit a few stitches with both strands together. There's several more ways, these are the only ones I know how to do.
Try the Russian or felted joins, near flawless and strong - always my first choice
You can also just start knitting like you do when add a skein when knitting flat. It helps to knit a few stitches with both the old and new yarns to prevent a gap.