So, this particular API is relatively simple to use. In fact, using the link above, you don't even need to write a single line of code!
This is a good place to start: https://developer.cisco.com/meraki/api/#!getting-started/base-uri
For the lock devices API call: You'll be able to do this through the UI itself...
You'll need:
- API key
- Network ID
- device IDs