Web Access - Hello World in Pictures
Click Here to Download Postman
You can download the configuration and import this file in to postman.
Don't forget to set your environment to the one imported above.

You can grab sample calls to get a token and some data here
Get a token - it will save it to an environment variable - then get some data :-)
Next Steps
Have a look at the example calls and create new postman calls to get each of the 'Information Domains' (chunk of data) that you need. You can try all of these out on the sandbox provided.
If the web APIs do not cover what you need, please check with us to see if you've missed something. If key data read / write isn't there then you'll need to consider on-premise APIs.
Web API coverage is not complete yet. Potential technical integrators must make sure that what we have meets their needs before committing to a web-only solution.
At the time of writing, Postman was able FOC for use. However, any use of another vendor's software / IP is subject to that vendor's Ts and Cs and License Terms. Compliance with Postman's license is the responsibility of the end user.