Baby sleeping positions?

Cece • • мαмα σf 3 •

My DD seems to HATE being on her back for some reason.. I don't know what to do besides let her roll onto her side by herself and let her sleep like that.. She is only 4weeks and 2 days old. She'll cry and cry when I put her down unless I put her down on her side. How can I get her to sleep on her back?