This blog post contains links to a complete demonstration of setting up and using https://github.com/blackboard/BBDN-LTI-Tool-Provider-Node. Shout out to Scott Hurrey & Eric Preston and his team (everyone you see on the commit list at the repo!) for all their work and help with this.
First things first: Read, and understand, the specification. We can't do that for you.
Video Part I. Setting up and running https://github.com/blackboard/BBDN-LTI-Tool-Provider-Node on your local box to use SSL. Prerequisite: Follow ALL OF THE INSTRUCTIONS in the README of the git repo to clone a local copy and set up Redis.
Video Part II. Registering your local copy of BBDN-LTI-Tool-Provider-Node (BLTPN) on the developer portal and using the values from the registration to configure your local BLTPN.
Video Part III. Registration of the 1.3 Tool in Learn, creating a deep-linking managed placement, using the link to create content with the BLTPN tool. Near the end of the video we look at how to use LTI 1.3 Names and Roles to get all of the users in the course the link was launched from.
Video Part IV. Demonstration of custom parameters from the Deep Link launch request and also a review of Names and Roles in that request.
The purpose of Names and Roles is to let the Tool Provider get all of the memberships in the course, and the role of each member with a call to one endpoint using LTI 1.3 security. Here's a screenshot of how this looks from the BLTPN - showing the first two members and their roles that were retrieved from the course.