There are several choices for e-learning platforms available, some of them are free and some of them are not (though some of them will give your organisation a discount if you are a public or non-profit education institution).
Activity 2: Ask around: Do they use any e-learning platform? Which one? What is their opinion about it?
One of the most popular pieces of software is Moodle, used by schools, VET, HEIs and overall any kind of organisation. Moodle is free, open source and actively developed, supported and extended by third parties. Google has its own popular solution called Google Classroom, which integrates easily with the rest of the Google Suite tools. Edmodo and Canvas are other very popular solutions too.
Activity 3: Choose one e-learning platform, create a course for your learners and make them enrol themselves into it.
Activity 4: Let them learn by experimenting. Divide the class in groups of maximum 3 people, choose a general topic for a subject (i.e. Biology) and assign each group a subtopic (i.e. Blood flow, Nervous System, etc.). Have each group create, inside the same course and under their subtopic, a lesson about it, with quizzes, surveys, a glossary and external resources. Let them familiarize with the interface for a few minutes before you help them find the way.