First of all, if they only come to this platform for the sole purpose of learning, then that journey is going to be a rough one. They will only focus on earnings and not to learn the whole thing. So firstly, you need to teach them the purpose of Bitcoin and what it stands for. What you can do with it. The blockchain technology is awesome if you can understand it. So tell them about this, refer to some articles that contains these informations. I guess this article here could help a lot because it contains so much information on blockchain. Then you can refer to this article that contains info about Bitcoin. You need full understanding on something if you want to get successful in that. When they get a grasp of the basic knowledge, they will try to reach out to you for more advance knowledge or find it on their own. One thing I say always is that, the thing you learn by your own experience, you will remember that for a long time. You have taken a good step to help your friends and respect for that. But never force or advise on a financial decision. That's all I will say.  Because you are doing a great job already. Be sure to keep yourself safe first.

[Note: I did not write those articles. So if they contain any wrong info, please do your own research on them]