Non-graphic, medically accurate guidance for a 20-year-old about masturbation: basic anatomy, safe step-by-step approach, typical sensations during arousal and orgasm, ejaculation explained in physiological terms, hygiene, privacy and when to seek help.
Masturbation is a common, normal activity. Because you said you have very limited sexual knowledge, below is straightforward, non-graphic guidance focused on safety, basic anatomy, what sensations are typical, how to stay clean, and how to protect your privacy. I will not provide explicit pornographic descriptions, but I will explain what happens and how to do this in a way that reduces risk of injury or embarrassment.
If you want more detail about anatomy, how the body responds physiologically, or about sexual health services, tell me which specific area you want to learn about and I can explain in a factual, non-graphic way or point you to reliable educational resources.