"-"; the hyphen, press the hyphen button on your keyboard. this is for things that you think of as 'hyphenated' (compound surnames, words that bunch together like seven-year-old)
"–"; the en dash, hold alt and press 0-1-5-0 on your numpad. this is for ranges, subtractions, and other things that don't feel like hyphens/em dashes. use your best judgement
"—"; the em dash, hold alt and press 0-1-5-1 on your numpad. this is for the grammatical usage—it indicates a longer pause that can sort of be a proxy for a colon, comma, or semicolon i think
("what is this, two days ago?"
–you, the reader)