Many people used AWS, want redirect non-www to www for avoiding duplicate content.
Following the steps below will resolve your problem:
Step 2: Go to CloudFront and create new Dist and in origin put endpoint of S3 bucket we created in pervious
Step and in CNAME writes mysite.com and Click Create Distribution.
Step 3: go to Route 53 and add New A record mysite.com (not need to add any prefix) and select Alias yes
And put CloudFront endpoint URL we created in step 2 example (xyz.cloudfront.net).
After the DNS changes, if you try mysite.com it should redirect to www.mysite.com.