If you would like to create a custom training plan including Lessons, Hacking and Coding Challenges, navigate to Admin > Training Plans > Change Plan Type > "Use a custom plan"
From here, you can choose to start from scratch to create an entirely new Plan or you can clone an existing plan to use as a template & modify for your custom plan.
If you choose to "Start from Scratch", you will be guided through the setup. Be sure to note whether you want to make this the Organizational default or a Team Training Plan.
Alternatively, if you choose to Clone an Existing Plan, you will be guided through which plan you would like to clone and can customize from there.