How to Apply Foundation and Concealer for Beginners :
If the skin under the eye area is dry or wrinkled, it helps to first apply a lightweight moisturizer and then apply the concealer. Concealers like this should always be applied before foundation. Applying them to foundation is just asking for trouble.
Stick concealers are applied to the under-eye area much the way a lipstick is applied to the mouth. Stick concealers can be applied over or under your foundation, depending on how much coverage you want–under the foundation provides less coverage and over the foundation provides more. Dab the stick concealer over the area in dots and then blend with clean fingers or a concealer brush.