The whole topic of drugs could easily be covered in 30 minutes. The only thing people under 18 need to know is this:
There are a large variety of different recreational drugs, each of which make you feel a different way, and which come with their own set of different risks and benefits
At some point when you're older it may be reasonable for you to try some particular drugs, but there are some drugs which are never safe for anyone at any age
No drugs are safe for you to do yet. Your brain is still in a developing phase, and drugs that might be safe for you to do later will be very harmful to you at this age. Even though taking a drug might make you feel good in the very short term moment, it very likely could make your growing brain become depressed as soon as you come down from the drug, and this can become intense sadness that you feel for the rest of your life.
So for now just know that drugs is a complex topic that you can learn more about later when you're older, but for now the details don't matter because all drugs will be harmful to you right now while your brain is still growing