Ok...I just got a white balance filter for my camera. I do not know how to set the white balance using the filter. I tried doing what the instructions said that came with. They said to set my white balance to custom and I don't have custom. Then it said to set my focal length on my lens to telephoto. I searched and searched and I can not figure it out. I tried pointing the camrea at the light source and it wouldn't snap. Can someone please help me? Thanks!