To crochet a hat for a newborn baby you must gather a lightweight yarn in the desired color, a J/10 size crochet hook and a yarn needle. The stitches that you must know how to do are a magic circle, a chain, a single crochet and a double crochet.
The first step is to create a magic circle as your beginning. For the first round, chain three stitches, and perform 11 double stitches inside of the magic circle. At the beginning of the second round, chain three, and then double in the first chain of the round followed by two double crochet in the remaining stitches. On the third round, chain three, and then perform two double crochet in the next stitch followed by a repeating stitch pattern of one double crochet in a stitch and then two double crochet in a stitch until you reach the end of the round.
The fourth through the 10th rounds follow the pattern to chain three at the beginning and then perform one double crochet in each of the stitches in the round. Rounds that follow the 10th round are volume for a desired edge that can be folded up around the edges. The number of rounds above 10 determine how big the edge is.