How?

There are two kinds of dashes, plus the hyphen. Each has its own special use.

The hyphen is the shortest of the three and appears on your keyboard. It is used to join hyphenated compound words—Few home runs were hit during the dead-ball era. The hyphen is also used to break words at the end of a line on your word processor when you have full justification and hyphenation turned on (I can't duplicate that effect here).

The en-dash is the middle sized of the three. There is no key on your keyboard, but most software has the glyph as a symbol. It occurs between numbers or place-names as a substitute for "to". The Labor Day weekend is September 1–3 this year. Or I plan to take the Paris–Milan train this October. The en-dash gets its name because the dash has the same width as a capital N in each font.

Like the en-dash, the em-dash must be accessed as a symbol on your word processor. The em-dash is the longest dash and on typewriters was represented by two hyphens --. The em-dash is used in place of commas or semicolons. It represents a longer, more emphatic pause than a comma, but not as long as a period. Churchill—clearly the most charismatic of the World War II leaders—was quickly driven from power following the end of hostilities. The em-dash is so-called because it has the same width as the capital M.

Both the en-dash and em-dash are used without spaces between the dash and the surrounding text.

I hope this helps.