전 요리하는 데에는 자신이 없어요. I don't feel confident enough about cooking 저는 춤과 노래에는 정말 자신이 없어요. I really don't feel confident about dancing and singing.

-에 자신이 없다 means you lack confidence in doing the activity. Btw this is a priceless resource: http://endic.naver.com