There are two things to do today, one of which is easy, and one might take more time, depending on your experience.

Write your own introduction and conclusion for each lesson.
The introductions should whet your member’s appetite for the content to follow. The conclusions should get them anticipating what’s to come in the next lesson.

Create bonuses. You can create these out of the PLR you already have or purchase additional PLR.

You now have your PLR content and a good idea of how long your course will run. Today you’re going to break your content up into the appropriate number of lessons, placing those lessons in the correct order.

Membership sites are AWESOME because you make a sale once and get paid over and over again.
But…
Membership sites suck because you have to create a never-ending stream of content.