Okay. See that Reply button at the bottom of the page? You can click it and if you click into the large rectangle amd press buttons on the thing in front of you with the lot of buttons, the letters which are on the buttons appear in the rectangular area (don't worry, they don't disappear from the buttons). When there are a lot of letters, they have certain meaning - they form what we call "words", single units of meaning, which can be combined into yet bigger sorted tuples, complexifying or modifying each other's meaning.
Other users of the forum are equipped with similar devices, which enables them to also put their letters on the screen. With these, you communicate.
Sorry, I could not resist.
Willkommen.