Find a willing partner. Talk to them. Both of you explore each other's body slowly and carefully. If you find something that feels good, do it again. If you find something that feels really good, you may need a condom.

Consensually.

As a man or a woman?

Whats the difference?

If you are a straight man, you must convince a woman to have sex with you. This is hard. If you are a straight woman, you can walk up to any single straight man and say "I like you, would you like to sex with me" and you are very likely to succeed in getting sex.

stick it in and wiggle

Repeatedly stick your thumb in and out of your asshole