There are two methods of working when crocheting in rounds: Joined rounds and continuous rounds
Round methods: Joined rounds
Joined rounds are useful when making stripes in amigurumi as there is no ‘jog’ or step up when doing a colour change. However this method creates a seam which may not be desirable.
1) Complete your magic ring and crochet the given stitches according to your pattern for Round 1, join with slip stitch.
2) Now you start Round 2 of your pattern. Chain according to your pattern. The number of chains here will depend on your next stitch: dc=ch1 htr=ch1 tr=ch2 (similar to a turning chain when working in rows)
3) crochet into the same stitch (ie. into first stitch of previous round)
4) complete the stitches according to your pattern until you reach the joining slip stitch of the previous round
5) Skip the slip stitch from the previous round AND skip the chain at start of round:
6) To finish a round when working in joined rounds, join with a slip stitch into the to first stitch of the round.
I use UK terminology, click here for a handy conversion chart to US terms