Most young people start to feel sexual desire when they enter puberty (read more about the hormones that cause puberty and sexual desire here) and this is perfectly normal. Sexual desire can be very strong and many young people masturbate to release sexual tension and to have an orgasm. Masturbation is a safe way to release sexual tension and does not harm anyone. If you are thinking about having sex with someone else, there is more information to find out if you and your partner are ready for sex here.
Orgasm
An orgasm is the pleasurable release of built-up muscle tension that can happen from any kind of sexual stimulation. Guys tend to reach orgasm more quickly and easily than women (although this isn't true for everyone). And women are more likely to orgasm from stimulation of the clitoris than the vagina.
During an orgasm, you may feel warm, your heartbeat will race, you'll breathe harder, your face and chest might get flushed, and you'll have muscle spasms in your genitals. It's often intense and feels really good.
Men usually ejaculate when they orgasm. Some women ejaculate during sexual activity, too. Most women don't ejaculate, but either way is normal.
Although people tend to think that having an orgasm is the "goal" of sex, many women and men get lots of pleasure from doing sexual things even if they don't have an orgasm. In fact, putting a lot of focus on having an orgasm can make you anxious, which can make sex less good.
Many people masturbate to release sexual tension and to have an orgasm.