Here’s a bunch of examples I’ve found….
- Example C Program: Listing the Certificates in a Store
- Example C Program: Using CryptAcquireContext
- Example C Program: Enumerating CSP Providers and Provider Types
- Example C Code for Opening Certificate Stores
- Example C Program: Sending and Receiving a Signed and Encrypted Message
- Example C Program: Signing a Hash and Verifying the Hash Signature
MSDN has these examples scattered around the docs
This website provides a good overview of the concepts along with cross-platform examples