Several functions add certificates to a store. Three of them, CertAddCertificateContextToStore, CertAddCRLContextToStore, and CertAddCTLContextToStore add certificates that are already in context form. CertAddEncodedCertificateToStore, CertAddEncodedCRLToStore, and CertAddEncodedCTLToStore, add certificates that start out only in encoded form.
For more information on encoding and decoding, see Certificate Encoding/Decoding.