how do I stop rocking my 3 month old ?

marli
Ok so my baby is 3 months old will be 4 months on Dec 16. So for her to go to sleep I typically have to rock her if not she throws her fit. I want to stop rocking her however. How can I  make the change, I feel like she's getting too big for me to continuously rock her to sleep for her to nap when other babies nap without being rocked. Any advice is appreciated !!