Wearing your newborn can be very different from wearing an older baby or toddler. I would consider newborn wearing for most babies to be the first 8-10 weeks. Once the baby has good head control then it becomes more baby wearing than newborn wearing.
There are some points to keep in mind when wearing your newborn. Before attempting to wear your newborn you want to make sure they are fed, changed, and not overly tired. Having a happy baby is a big plus when trying out a new carrier or carries. Your newborn can be worn with legs in or out of your carrier, depending on your and baby’s comfort and what carrier you are using. For most soft structured carriers you would need an infant insert which means legs in for the newborn. It is important to pay attention to your newborn’s cues for comfort and to make sure their airways do not get compromised. You should always be able to fit two fingers under your newborn’s chin while you are wearing him/her. Supporting your newborn’s natural, c-shape spine position is also an important thing to remember. When you pick up your newborn and put them on your chest, the position they naturally take should look very similar to how they look once they are in the carrier. Newborns need to be worn high up, close enough to kiss and nice and tight to prevent slumping in the carrier.
I am including links to some graphics and babywearing videos that are helpful for newborn wearing.